So.......I stumbled upon this particular older Sigma 24mm f/2.8 macro lens. I kinda want one for Pentax but haven't found it yet.

Reviews:
http://www.photographyreview.com/mfr...6_3111crx.aspx
http://www.dyxum.com/reviews/lenses/...asp?IDLens=215
http://www.photozone.de/pentax/144-s...ab-test-report
http://www.photodo.com/product_433_p3.html

There's a shitload of them for Nikon. Pre AF-S so will not AF on bodies that require AF-S lenses.
http://cgi.ebay.com/Sigma-Super-Wide...item3ca9666f51
http://cgi.ebay.com/24mm-2-8-Quantar...item25585da316
http://cgi.ebay.com/SIGMA-SUPER-WIDE...item45f071be78
http://cgi.ebay.com/Sigma-Super-Wide...item2304e297b3
http://cgi.ebay.com/Sigma-Super-Wide...item1c0ef7671b

There's some for Canon but they may or may not work with the DSLRs. But here are a couple Minolta/Sony ones:
http://cgi.ebay.com/Sigma-Super-Wide...item25585eefcf
http://cgi.ebay.com/SIGMA-24mm-AF-Su...item35a679374c

You can even get the proper hood for it here:
http://cgi.ebay.com/Sigma-Perfect-Ho...item2304e2afeb