Watch this Pentax K1000 get cleaned and refurbished
One of the earliest cameras I ever shot on was a Pentax K1000. It's one of the gold-standards of film photography and often suggested to film students who are just starting out and need a reliable and affordable camera to play with (you can easily find this camera for under $100 on eBay).
I still recommend this camera to people who are looking to buy their first film camera (odd thing to say, but yeah...). Watch this video of one being completely gutted and restored to near-original beauty.