I don't know anything about Ebay (have never used it) but I know a bit about Polaroid cameras. Personally I wouldn't call the colours crude but the quality is not as good as conventional film. They have made a whole range of cameras over a 55 year period and as a result there are a lot of different film formats, not all of which are still available.

The very earliest took their own type of rollfilm which are no longer available. Then there was a long series of simple box type cameras and more sophisticated folding cameras, some with rangefinder, which took a filmpack which consisted of originally 8 (now 10) individual picture sheets which each had to be pulled out of the camera and the picture then peeled off the backing paper. These filmpacks are still available in colour (eg Type 669) & B&W. You do not get a re-useable negative except with one specialist B&W film so the print needs to be rephotographed or scanned for further copies.

The problem with many (all?) of these cameras is that they require a 4.5 volt alkaline battery called PX19 which can be very difficult to find though I think Silverprint did or does still stock them. Fuji also makes colour filmpacks which fit though I am not sure if the speed is compatible. These cameras were originally designed for 80ASA (colour) & 3000ASA (B&W).

Some of the boxtype filmpack cameras took a square picture and I'm not sure if these filmpacks are still made.

The SX70 was I think the first Polaroid film that was integral ie there was no peeling involved. A number of cameras were made for this but next Polaroid introduced cameras that took a faster integral type film - the 600 series. They still make cameras for the latter and both 600 series & SX70 film is still available.

There have been other recent Polaroid formats and a couple of Fuji ones.

My guess (and it is that) is that the best place to start looking for any of these, secondhand, is at charity shops & car boot sales. Many would have been bought by casual snappers who have probably gone over to, dare I say it, digital so there must be stacks of these old Polaroids floating around somewhere. Myself I love the folders if you can get the battery, I still have one myself which I refuse to part with!

Best of luck.