Upon Diana and Raf's recommendations I picked up the Nikon 60mm f2.8 micro (Nikon calls their "macro" lenses "micro" lenses ...). The reviews on it were great and it's not terribly unreasonably priced if you're budget conscious.
http://canreef.com/vbulletin/showthread.php?t=36153&
This is an ebay ad from the same place I bought mine from (KEH Outlet):
http://cgi.ebay.ca/60mm-f2-8-Nikon-D...QQcmdZViewItem
Mine had the same description (ie, "used" "70% condition of new") .. which worried me a little until I saw it. The optics were in perfect condition, any wear is on the surface due to handling etc. and that doesn't concern me too much since it doesn't affect the function or performance.
Anyhow, maybe food for thought... I like the lens, it's just about the only lens I use now for shooting my tanks. Unless I'm using the Olympus which is better for the top-down shots since it fits in the canopy
