Tamron 28mm 2.5

https://secure.ffordes.com/Shop/Store/Itemdet.asp?Type=secd&sub=1&Code=P...

Anyone have any idea if this would be a good buy? Would it act like a KM or KA mount?

also found a czj one for the roughly the same price.

http://www.charleseaglesandson.com/used%20carl%20zeiss%2028%20pk.htm

I've got one of these lenses - had it for getting on twenty years. In terms of image quality, it's a cut above the typical 28mm lens and was generally very well reviewed whilst available. By way of example, I bought a Pentax A 28mm lens recently and tried them side by side. The Tamron gave the Pentax an absolute kicking in terms of resolution and contrast and it wasn't until about f8 that results started to come together. The Pentax was returned to the shop. I'm very happy with mine as it acts like a fastish wide-standard lens on my K10D.

You could luck out and get a version with a KA bayonet mount but I'd suggest dropping them a line before buying to check. Don't be too disappointed if it's the plain vanilla K mount though. Tamron Adaptall II mounts in KA bayonet tend to go for £50-£60 all by themselves so you'd get an absolute bargain if one of those was included. As it is, £29 is a pretty fair price for a good lens.

Adrian