In 2007 (I think) I saw a 29-8 Mountain Gun at H&H Guns in Oklahoma City for $650 and pounced. I think it was a good decision.
It's is a fine-looking gun, especially with the "Mountain Gun" grips.
It's performance is the same as any S&W 29 so you can't go wrong there.
A few years later I saw one for sale at $770. Lately on Gunsamerica, GunBroker, etc. asking prices seem to be around $1000, but the guns seem to be few and far between.
Frankly, it's lower on my list as a field gun because I believe my 629 Mountain Gun is probably more resistant to weather. I hand load for both (all my 29-series guns), generally working up loads I got from John Taffin to fire 240-gr bullets at about 900 - 1,000 fps from the 4" barrels.
I don't buy to resell, or stock a museum. I shoot 'em or I dump 'em. The 29-8 is a keeper.