Im 13 years old and just starting to get into photography. I trying to find a good instant camera under $100
Your best bet is probably a point-and-shoot digital camera rather than an "instant" camera. That way you're spending more of your money on the part that records the image rather than the part that prints the image, and you don't have to worry about the expensive consumable cartridges those cameras require. You can also print your photos at any size, whereas the "instant" cameras only give you one or two (tiny and tinier) sizes. You can have your digital photos printed at any local drugstore for maybe 15-20¢ each, or you can use your photos in digital form at no cost at all. Contrast that with Fuji Instax film, which will cost around 70¢ every time you press the shutter button and doesn't give you a digital version of your image.
Check someplace like Amazon to find reasonable deals on compact "point and shoot" digital cameras -- there are plenty in the $100 range. There are a number that offer sensors up to around 20 megapixels for that price. Remember to reserve a bit of your budget for a memory card, but don't spend a lot on those -- you can add more later, and they're always getting faster and cheaper.