Yes, Ari, all the decently priced pack-film Polaroids are old cameras you'll need to get via eBay or similar. FWIW, these were expensive cameras when new; the 250 sold (in about 1964) for a sum that would fetch a fair to good used car (at least in the USA), and you'd be seriously challenged to find a used car that even runs for the $800 they're getting for the Konica Press Instant (and you'd better hurry on that one, as Konica recently dropped all film camera manufacturing, which likely includes that model).
I'd recommend the 250 and 350 models. They're likely to have non-functional shutters as received from a know-nothing eBay seller, but that's easily corrected, since it's practically always due to corrosion in the battery connecting wires and you'll probably want to convert it to use 2xAAA cells in place of the 532 that was original in these models (the 100 used a 531 that was 4.5 V and would require 3xAAA). I've made this battery conversion on my 350, also including connecting the development timer to the same battery as the shutter (original had *two* 532s), and it fits in the original battery compartment.
You should be able to buy the cameras for under US$20 plus shipping, convert/rewire the batteries for $5 or less in parts and do the work in half an hour to an hour, and have a fine working camera. The down side is that it's auto exposure only; that can be corrected by stripping off all the original shutter electronics (unfortunately also removing the original lens, which is quite good on the 100-250-350-360-450 models) and replacing it with a lens in conventional shutter mounted to the or extended from the original front plate. Suitably adjusted to give infinity focus at the camera's original infinity position, you can use a 120 mm from an old 116, or a 127 from a different Polaroid or a 4x5 press camera, and still have usable rangefinder accuracy (within DOF as long as you don't shoot wide open at a close focus setting - f/8 recommended inside about 6 meters, f/16 preferred up close). Depending on the lens, you might even be able to mount a 105 mm from a 6x9, which should barely cover the almost 3x4 Polaroid pack film.
And then, when you can't get Polaroid film any more, these are easily converted to 4x5 and make nice, lightweight 4x5 RF cameras (though they aren't so good for ground glass focus).
