How much should i spend on an old film camera?(First camera)

I suggest keh.com, especially if it's your first film camera and you want to be sure it works well. They have decent prices, and one thing to know is that even their "Bargain" rated equipment is usually in very very good shape. And if something isn't right, they have great customer service.

I pulled up some Canon manual-focus (mostly AE-1) body-only: Canon | KEH Camera

There's a wide range, you can see, depending on the condition of the camera. "Like New" rated cameras are going for over $100, but other "Excellent" rated bodies are going for less. It seems you can get a 50mm for less than $100 in the FD mount: Canon | KEH Camera

 

That is totally overstating things. Can you get a Brownie or an Instamatic, or a cheap Vivitar point-and-shoot? Probably. But a Canon AE-1 in working condition with a fungus-free lens? No, you're not going to get one of those for "just a couple of dollars." The OP is not in the market for a 50-year-old Bakelite camera.

In fact, I'd say film camera prices are going up lately because of a higher demand as more people are trying film for the first time or going back to film. A K1000 body used to go for about $25, but now they're fetching 2 or 3 times that much for a kit in good condition.

Of course, now I have to highly recommend the Pentax K1000 or Spotmatic. Basic camera, workhorse construction, great lenses, and generally, you're going to get better value for your money when buying Pentax as opposed to the big names of Canon or Nikon. Even for old film cameras, those two brands still carry a price premium for brand recognition.

 

OP, you might also want to check out an Olympus OM-2 or a Minolta SRT. Both excellent cameras with great, sharp lenses.

 

It depends on how much of a chance someone wants to take on what they are buying. Someone who has an idea of what to look out for will do better with private sales. Someone new to film cameras might want to feel more secure with an established business that has an easy return policy. In the end, the prices for gear of comparable quality end up being not all that different between an auction site and something like KEH.

You'll also note that none of those cameras were selling for free or just a few dollars.

 

Even $35 is not "just a few dollars." And will the camera work? Because people never lie on Craigslist