I have heard of a street in Tokyo (Sinjuku sp? i think ) that suppose to be the place to be able to find cheap used camera.... not sure where exactly. but will be interesting to have a wonder... like you said, it would be good to be able to find an old gem...
However, at the same time I dont want to go there with a false expectation to be able to find a good lens and not bring a decent one along to take normal photo....
I went to a local pawn shop and found a old sigma 28-80 f3.5-5.6 that is pretty small in hand... plus at $20, it should work well as a disposable one, but handy enough for those shots if I do need it...
Will be picking up the 15 today... have a outdoor wedding tomorrow so would be a good time to test it out with my old 50 f1.4 in my jacket pocket