I bought a minty M29 exactly as you described yours. I paid $425.
I bought a 6in M29 blued with some wear. About 85%, mostly at the muzzle from holstering. Gun shoots accurately, and cylinder is tight. I paid $325.
Tell your wife you need to keep a piece of nostalgic history, because cash "ain't" what it used to be.
Buying a 460 S&W will probably set you back between $950-$1050. You can scrounge another $400, instead of trying to eek out $600 plus cash, right?
They do NOT blue guns the way they use to anymore. That is the main reason you want to keep your Model 29. It is all stainless and some kind of baked on blue stuff now.
The dealer will give you $275-325 so he can make his minimum of $75-150 on the handling and resale.
It is just cash, man. Take the wife out to dinner and the theater to cool things off.......
I NEVER sell any of my guns.........Especially the nicely blued ones of yesteryears....