Sorry for getting in here late, I've been having worse-than-usual computer problems. Anyway, I won't torture y'all again with my bargains. I'll just say that it's hard to find BAD manual primes at 28-35-50-55-58-100-135mm. If you want brand suggestions, try (in absolutely no order):
Vivitar, Ricoh|Rikenon, Takumar, Sears, Chinon, Focal, Jupiter, Zeiss, Albinar, Helios, Sigma, Lentar, Industar, Tokina, Yashica|Yashinon, Petri, Steinheil, Mamiya-Sekor, Zenitar, Porst, Meyer|Pentacon, Mir, Tamron, Enna, Toyo|TOU 5-Star, Cosina, Soligor, and Isco.
Many of those will be in M42 screwmount and some are M39 (mostly Jupiter and Helios) -- these need simple adapters. Some will be PK mount, with no adapter needed. And Exakta-mount lenses (without the stop-down button) are very easily adapted to PK mount. Just remember these simple rules:
* If it costs less than a sandwich, buy it; if more than a good meal out, think real hard about it.
* For auctions: Bid low; bid often; lose 99%; don't sweat it, another will come along immediately.