If you're able to find an older working camera, awesome. To quickly test it, press on the shutter button, and if you hear a distinct click it should be good. The newer or restored cameras can be super pricey. The film is also very costly. Polaroid stopped making the original film, and a another company called Impossible Project makes it now. The formula is different and can be tricky to work with. You need to shield the film as soon as it pops out. Then you need to keep it somewhere cool and in the shade for about 20-30 minutes to let it fully develop. Over time, the photos may have a green tint. You also have the option of black and white film for Polaroids.
This camera produces credit card size photos. The quality and color of the film is amazing. It happens to be the cheapest film, plus you can pick up a pack at both Walmart and Target (the Polaroid 300 film works in these cameras). There are several versions of the Fuji Mini to choose from, or you could go with the Polaroid version.
This camera produces a wider photo (which I prefer to the mini). Sometimes what you see in the viewfinder isn't always what you photograph. Great quality/color film. This camera and film is pretty reasonably priced as well. I've only been able to find the film on Amazon or at specialty camera shops.