www.tradingpost.com.au has a listing for: Pentax F1.2 50mm lens, excellent cond, $185 (03)98002825 Wantirna (not mine). That area code is in Victoria, from other countries you would dial 61-3-98002825.
It looks like a good price ($Aus1.00 = $US0.74), but I can't vouch for it's condition beyond the sellers description (no photo but that's not unusual on this site) The actual web page is <http://www.tradingpost.com.au/browse.asp?State=NSW&sMsg=Search> but that's a search result so you may have to enter via the home page above, choose Victoria on the map, choose the "audiovisual" category and the "photographic" sub-category, then search "Pentax". After all that it could have sold already but you'd never know without enquiring. Just a heads up, especially for new *istD owners looking for a fast portrait lens. As it's not an auction I guess it's OK to spread the word. regards, Anthony Farr
