I have a set of these eyepieces. With an eye towards binoviewing in the future, I snapped up a second 5mm when it became available because they are so hard to find. I am willing to sell it however, because its not being used and there are other toys I need.
Condition is excellent, some minor marks on the barrel. Comes with both caps. It's offered at what I paid, $350 + ship and insure (firm). If you'd like I'll throw in a pentax o-5 box (non-smc). No Paypal, postal money order preferred.