Value depends on the particular gun - some 29s (and S&Ws in general) are great and some just weren't put together or finished quite right for whatever reason. If you aren't an expert have someone who is look at it. 'Like new' is tricky and can be faked.
If everything is Kosher $600 is probably in the ballpark - depends on the gun and how much yuo want it.
If this is an auction be sure there is a no questions return policy. If not, pass.
Does it have the original box(es) and tools and papers? That's worth something.
Nickel is not more valuable.
Shorter barrels, 4" and 6.5", are bringing higher prices now than the longer barrel versions.
No probelms with lead bullets in nickel guns. Be careful what you use to clean them, some chemicals attack nickel. Sooner or later the plating will wear or flake if you use it. Re-plating is fairly inexpensive. I like nickel and shoot my nickel guns.
