As a reference, there was one on ebay last week that looked perfect, was in a copal (which I'd prefer and newer) that started at $475 and no one bid. I bought one ages ago, when these were worth more and it was about $325. It was a 1959 issue. I gave it to a friend of mine a year ago and I figured it would bring about $250 without issues had I sold it.
There is one at KEH (which is pretty inconvenient for you) that is listed as "bargain" at the $310 mentioned. From the pictures, this one looks 'bargain' to me. That front element looks grungy (indicating less than fantastic care) and the lens looks to have seen some miles (kilometers). From the serial number chart, this one is pre Feb, 1957. If you are buying it from a private party, then $250 is my guess, but you should have the right to return and you should check the shutter speeds (have them checked before you buy if you can). If you have to have the shutter fixed, it's going to be $100 or more. I wouldn't expect the speeds to be perfect, but I would want them stable and the lower ones from 1/2 to 1/25 should be useable.
Buyer beware and lucky.