Below is a list of my favorite "tools of the trade" for alternative dessert prep. These are thing things I actually use in my own kitchen, with notes about what I use it for. Hopefully this points you in the right direction if you're feeling uncertain about your next purchase. Most of the below are affiliate links, so if you'd like to support the site, any purchase you make through those links will help (without costing you extra).
BLENDERS
Vitamix - You need a good blender to achieve a really smooth consistency with your desserts. This is the queen of blenders, and what I use pretty much non-stop in my kitchen. I personally really like the dial knob for adjusting speed. If you're shopping for one, they've got a newer low profile model out now that basically has a wider jug, making the whole unit shorter overall and easier to fit under cabinets. Which is great, but the downside of that: it doesn't work as well for blending smaller quantities of ingredients. The taller classic size jug is better for blending smaller quantities, so just a consideration to keep in mind.
Froothie Optimum - For you Aussies, I know Vitamix is super expensive over there. When I was visiting Australia, I borrowed this blender from a friend during my stay and it was excellent. Just as powerful and high quality as the Vitamix, but much more affordable (for those in Australia). Also available in the UK.
Magic Bullet - I use this to blend very small quantities of ingredients, for when a Vitamix would be overkill. A lot of people also like this one, made by the same company but nicer blades and more expensive.
FOOD PROCESSOR
Breville Sous Chef - I love love love this food processor. It's amazing, heavy duty, fairly quiet as food processors go, and can handle anything you throw at it. It's got two bowl sizes, so you can do large or small batches of ingredients, which is brilliant. I expect to have mine for many years to come. This was a recent purchase for me, after tearing through a string of cheapos. The biggest obvious con is the price. If you can't afford one now and you're serious about making a lot of alternative desserts, get a cheap one and then save up for this in the future, or keep hinting to family and friends when it comes time for your birthday or other holidays :) These are branded "Kitchen Wizz Pro" in Australia.
PANS
I like to make smaller portion desserts, so I find that having a range of smaller pans is more cost effective. Alternative desserts, by their nature, are rich so you don't need huge portions anyways. Over the years I found that a regular size 9” pan is way too big unless you're serving a large number of people. So below are the pans that I use every week.
6" Springform Pan - I recommend getting a 6" springform pan with tall sides. With the high walls, it gives you the option to stack your ingredients right up, and make taller multi-layered cakes if you want to. The 6" cake size looks particularly good when stacked taller, and if you're making a shorter, flatter 6" cake, you can still use this same pan just without the extra ingredients for extra layers, so it does double duty.
Mini Tart Pans with Removable Bottom - For making cute mini sized tarts. 
6” Regular Cake Pans — I recommend having 2 -3 for smaller sized baked layer cakes.
6 Cup Muffin Pan - This is handy for making smaller portions of muffins. If you don't fill up all the spaces in your 12 cup pan (like if you're only making 6 muffins), it can warp in the oven due to heating unevenly and could splash your batter. So I like having the 6 cup one on hand for this reason. If you have a 12 cup pan and want to just use that to make a smaller number of muffins, make sure to fill the empty spaces with water. 
Mini Silicone Cupcake Liners - These are good for making tiny cakes (like these Blackberry Lemon Cheesecake Bites). They are also great for using up any extra surplus of cake filling, for making small chocolates, that kind of thing. You'll want to place the liners inside a mini cupcake pan for stability. 
Silicone Cupcake Liners - These are regular cupcake size. Good for making chocolate cups and smaller sized freezer desserts (due to them being easy to pull off). 
Silicone Chocolate Mold - For pretty chocolates.
OTHER BITS & BOBS
Long Handle Measuring Spoons - I'm very particular about my measuring spoons. Getting ones with long handles and narrow heads means you can scoop down to the bottom of spice jars easily, getting every last bit out without getting your hands all messy. 
Decorating Pen Tool - Used for writing on cakes, piping patterns, drizzling chocolate, etc. with more precision. 
Linzer Cookie Cutters - Handy not only for linzer cookies... The tiny shapes can be used for patterning, tiny cookies, fruit cutouts, and the larger cutter can be used without the shapes for round fluted cookies. Multi-purpose = good value. 
2 tablespoon Scoop with Trigger
1 tablespoon Scoop with Trigger
I use both these size scoops for making cookies usually-- like macaroons-- or just to evenly divide the batter. They also come in handy for scooping out sticky ingredients from jars -- like coconut oil, nut butters, and things of that consistency.
Nut milk Bag - I prefer a nylon mesh nut milk bag. I've tried various other materials that are more natural (like cotton) but I find that nylon is just easier to clean thoroughly (no moldy bag later). Also, I really like the ones with rounded bottoms because it fits easier into the bottom of a bowl when you're straining. 
FOOD
Below are some of the more unique edible ingredients that you might want to order online if your local stores don't stock them.
Raw Ground Vanilla Bean Powder - Really good flavor, and an all around wholesome product. 
Instant Espresso Powder - Another beautiful flavor, enhances chocolate or coffee-themed desserts. I like using it because you don't need a lot of liquid, so it's easy to work with when you don't want to destabilize an existing recipe by adding too much liquid to it. 
Maqui Berry Powder - Gorgeous flavor and an easy way to color things purple naturally. 
Unsulphured Blackstrap Molasses - Good in gingerbread type recipes. It really shines in chocolate recipes, where it can impart a rich, malty flavor to the chocolate. 
Cacao Butter - Adds a rich, deep chocolaty flavor. It's a good alternative to coconut oil in many recipes. 
Coconut Butter (Coconut Manna) - This is not the same as coconut oil—it's made from actual blended coconut. It's useful for frostings, thicker recipes, and goes great with chocolate. 
Unscented Coconut Oil - A good alternative for those who don't like the flavor of coconut in desserts.
Rosewater - My absolute favorite brand, very nice exotic flavor. 
Orange Blossom Water - Another exotic flavor I enjoy using.
FLOWERS
Edible flowers are a cornerstone of my decorating arsenal, especially for raw cakes. Below are a few of my favorites.
Blue Cornflower Petals - These add a vibrant touch of blue or purple...but they also come in a variety of colors like pink, fuscia, and yellow 
Lavender - Love using this paired with chocolate, to add a purple hue to the top of desserts. It has a strong flavor, though, so only use a little bit unless you really like a strong lavender taste.