I have noticed that recently F2's are going for a little more than F3's for some reason. Either one can be had for less than $300.00 in near mint condition, the exception would probably be an F3hp or most certainly a F2as, F4's are going for a song as well. F5's would be pushing the limit of your budget. My personal favorite is an F2, they are just tough camera's that can take whatever you throw at them. I have an F4 as well, but find that I don't use all the auto stuff anyhow, but it does have nice metering. If weight is an issue, there are as mentioned, FE and FM's, very reliable as well. F100's have great reviews, but I have never held or used one, I am just not that big on automatic stuff.