Someone mentioned the Trooper .22s. These are sort of interesting. They're basically Officers Model Match guns with 4" barrels and generally shoot very well.
They were only made from '54 to '61. We seldom know just how many Colt made of anything, but I've seen figures on this one of 2,000 and 3,000. Whether either number is close to accurate, I don't know. Trooper .22s aren't rare but you don't see them for sale every day. They were used years ago by some law enforcement agencies for training before moving on to .38s.
I don't know what these guns sell for nowadays, but a few years back they really didn't bring much nor did there seem to be much demand for them. Great .22s.