When doing cake smashes, we get a lot of theme requests that we'll likely only ever do once and then never again. I HATE buying expensive themed backdrops that won't get much use. So I've experimented over the years and come up with some cheap hacks and most cost around $20!
I have found that an easy hack is to buy fabric shower curtains. Keep in mind that this only works with the FABRIC ones. Plastic is going to reflect.
I prefer to buy the widest I can find. Shower curtains are usually a bit more sheer, so you'll need to put some fabric or something behind them to give them a solid look typically.
With this ice cream shower curtain I tacked it to my wall to make it look like wall paper, you can see it's sitting against my crown molding. Shower curtains have a rolled edge, that you can see in the bottom. If you put the backdrop to the ground and put a flooring over it, that would hide that issue. This cost only about $30.
Other good ones:
I have used this beach one.
This mermaid one is one of my favorites!
You can pickup the mermaid shower curtain I bought, here.
A good rainbow one would be good to have on hand,
I'm waiting for a good chance to use this circus theme one!
I can't find this one off hand on Amazon, but I once did a Finding Dory theme smash and used a shower curtain.
Tons of brick options.
There are several Harry Potter options and you can't beat that price!
There's quite a few Cocomelon options even
You could also use paper or wall as a backdrop and just add wall decals. I did that with a Peter Pan request once.
That decal kit was this one:
One thing to worry about with the wall decals is that they are typically glossy so they may glare in images. You'll want to try and feather your lighting to prevent some of that!
For this one, I cut the paper off when I was done and rolled and saved it, just in case I ever get that request again.
You'll also see wall tapestries on websites, these work great also. Although they are typically a little on the smaller side. Some of these you could also use as wraps or layers as they are softer and bend/flow easier than shower curtains.
I don't even remember where I bought this mermaid one from. I sometimes see tapestries in online clothing shops.
Need a princess castle?
Winnie the Pooh?
Have a space or astronaut theme coming up?
Among us is so popular right now:
This would be gorgeous for a llama or cactus type theme:
Keeping that same theme, this is a gorgeous slightly girly dessert scene:
I have this brick one, although I don't know if I've used it yet!
This colorful brick one is actually a good one I have used on occasion in studio. I tacked it to the wall with clear tacks.
This next one is a really pretty one with girly, floral, boho vibes:
There are tons of floral ones. This one JUST got added to my cart!
Is that Hogwarts?
If you're looking for wood look, I have this one, although I don't think I've used it yet!
In a pinch, you can also go to the craft store and pick up fabric. I usually get 2 yard increments. I find that the best kind of fabric for backdrops are the Home Decor type fabrics that Joanns sells on the rolls. They are heavy duty and more stiff typically.
These are two flamingo patterns I found in fabrics: