Any tips for buying a Polaroid?

TLDR Got bad luck when trying to buy a Polaroid for nostalgia, bought two dudes. Out $40 in film and $50 in cameras. What am I supposed to be looking for here so I don't get fried again? :')

Got the urge to buy a Polaroid to relive my childhood a bit. Decided to pickup a supposedly working Sears edition Pronto from a photographer on Craigslist. Ended up being a dud. No power so I opened it up, absolutely corroded inside. Cleaned it up best I could and I get life out of it but the shutter wouldn't activate and I'm fairly certain the motor for the film is toast. Decided no big deal, Ill buy a more recent model. So I settled on a 600 One step from another person that also said it worked. This time I brought a film pack to test it in person. Worked perfectly, no problems. Paid the man and left happy. Until I tried taking another picture when I got home. Shutter works but doesn't trigger the motor. Tried all the recommended fixes nada. Figured ok maybe the battery in the cartridge is low. Painfully swapped out the film packs knowing I'd be wasting film. With the new pack, It ejected the dark slide normally but same thing, no motor when I take a picture. Even tried adjusting the pickup and moving the gear in the top left a bunch until it clicks several times. So now here I am, with two paper weights, a $90 hole in my pocket, a singular picture of my car, and sadness.

I know the GO cameras exist but nostalgia was getting to me. Anything I should look for or do I give up on the vintage dream?