They exist and aren't really strictly collectors pieces. You see them come up on gun classifieds and under the LGS counter from time to time. There is a bit of a premium on them, but not too bad. If you can find one, you should be able to buy it for $500-700, the .357s and .38s typically go for $300-$500. I'm sure some have sold for more, but I don't think that is typical.