In July 2015 an unfired specimen in bright nickel with original box, papers, accessories sold on Gunbroker for $3,250.
Engraved and nickel plated Smith Wesson Model 29
It is very difficult to accurately price a rather rare firearm- there are simply not enough sales to compare it against. Your gun was likely a product of the S&W Custom shop, and should be appraised by an actual firearms appraiser. S&W customer service can help you locate one. Value is likely at least $2000 US, and possibly higher. And thank you for enough of a description of your gun to get us in the ballpark. Usually it is "What is my Winchester worth?"
Nice revolver
I purchased a "wyat earp" commemorative pistol 20/25 odd years ago. its nickel plated & engraved. unfired 45 long Colt 8" barrel > originally by American Historical Society. paid $1000 +/_
50-150 USD
50-5000 usd
20-80 usd
50-1000 usd
50-500 usd
60 or so
Pi Squared
50-1000 usd