The snubby M15s are less common than their 4" barreled brethren; nickel makes it even less common still.
bamabiker is right, though, even in this configuration, it can't be called "rare", and without more facts about the gun (condition, box, papers, tools), it's near impossible to adequately advise.
Here are two recent threads on gun value, one for a blued 15 snubby, one for a nickeled 10; reading them should help you with how to think about valuation of your piece in the current market:
S&W Model 15-4 Mint!!!! (((UPDATE))))
10-8 Nickel 3"In Box Price Check