If you're lucky, you'll find a beautiful custom bike on ebay that was made for some basketball player who no longer wants it. The pool of people looking is small, so you can get a good deal that way (i saw it happen a year or two ago!)

Next up, there are occasional sightings of frames from 64cm to 66cm out there but they are extremely infrequent. You would probably be OK on a frame that size if you can find one.

Or... just spiff up your existing bike and ride that one. You can still find repair parts and tires in that size, so there's no reason you can't still enjoy it.