Best way to get reliable info on current national gun values and prices is to use Advanced [Search]/Completed Items on Gunbroker.com.
[Some use Fjedstad's Blue Book. But Fjedstad's is just a shot in the dark compared to the real national market for actual sales on Gunbroker.com.]
Anyhow, on the first page of 50 closed items, these prices were found for recent S&W 629 actual sales:
$635 (Dropped and damaged firearm)
$769
$800
$875
$1249 (Weighted barrel and other extras)
All the other listings either closed out w/no bids at all (most), did not meet seller's reserve price, or were otherwise withdrawn.
My guess on appropriate trade value for an S&W 629-2 would be in the $800-$1000 range, depending on condition, accessories, extras, etc.
You can go to Gunbroker.com, login (gotta log in), and check the completed listings for yourself.
Informative.
BTW: That Sucker will Rattle Your Teeth. (And be hard to carry concealed.)