A lot of people in this thread are giving you weirdly specific advice about precise items to buy…
I noticed you’re considering buying a 3D printer with that budget. I think the answer depends somewhat on how often you come across money and what else you might spend it on. It’s good to be careful with your money, but part of being careful with it is doing some research to figure out when an item is too cheap to be worth it for you. There’s no one answer because it depends on what you value. In terms of the 3D printer, consider how much it will cost to run it, how much you want to use it, and what you might get out of it. I don’t know much about 3D printers, but I suspect if most people are telling you to get a $200 one instead of a $100 one it’s likely that the experience with a higher end one is noticeably better and less frustrating. If the quality of the parts is important to you and you’re not willing to put up with frustration when prints don’t work, or the printer needs maintenance, the extra money is probably well spent if you do want a 3D printer (and cheaping out might get you a 3D printer you won’t be happy with, which could be a bigger waste of money than a safer but more expensive purchase).
There are other options to consider. Libraries near you might have 3D printers you can use, and there are places to buy 3D printed models online (if you just want somebody to print them for you and are more interested in having some mini figures instead of the process of 3D printing). Buying 3D printed models from somebody else may cost less than getting a 3D printer, unless you think you’re going to make heavy use of it. It’s possible that you could also sell 3D printed stuff to recoup some costs if you do get a printer, but when making the decision I think you should assume you’ll make $0 from it and make sure you’re okay with the purchase in that case anyway.
My general rule of thumb is to wait a week or two before buying anything and then I’ll buy it if I still have the itch and am obsessing over it. There are always more sales too (and Black Friday deals will be going on all month). A 3D printer seems like a good purchase for a teen to me. There’s some cool skills you can learn that go alongside it. If you haven’t already look into some of the free software for creating models for printing (tinkercad, blender, etc). That’s a hobby you can get into with no money and might influence whether the printer would be worth it for you (can you make the things you want to make, or do you want to print models that others have made?)