I've got a Renwal Aeroskin F11C-2 Goshawk that's pretty tough to find these days as well as several Aurora P-40's and an Aurora P-6E.
One which has been eluding me for ages is the 48th Revell '1941' P-40 kit. That was only given out as a promo, mostly at the theaters, and is considered by some to be quite the collector's item. Had my chance to grab one on two occasions and missed out because of procrastination.
One of the more unique items which I've had in the past, which I had inherited from my Dad, was the Testors Miss Budweiser Hydroplane. Had two of those, but made a small fortune with 'em on evilbay.
Oh and another hard to find kit I have is a 1/6 Playful Betty Page by Screamin'. As soon as I can find a buyer for that one, though, it's gone...
Fade to Black...