Bear in mind that you may need to get the shutter serviced. I bought a 124 off this forum a few years ago and it cost me about 2/3rds what I'd paid for the camera for a CLA, however it was worth it.

I love using my Yashicamat they are fun and easy to use quickly, I don't need to be as precious with it as my Rolleiflex so I don't bother with a case. Unless the 635 is a very good price you might be better waiting for a 124 or similar with a Yashinon lens.