I've got a Yashica Electro 35GSN. It matches most of your requirements, it's very quiet, excellent ultra-sharp f1.7 45mm lens, aperture priority. It's not that small or light though. On mine the light seals are just starting to go, but it's a very nice camera. See www.yashica-guy.com for loads of info on them. I used it to see if I really did like RFs as I was hankering after a Leica. In the end I got a Bessa R2.
Yashica's usually go for much less than 80 pounds. In fact, now I've got the R2 I'm hardly using mine so I'll be putting it on eBay after half term next week. pm me if you want to try it out.