I asked this same question months ago when I was shopping for a 629 yet couldn't find one for under $1000 dollars.
As near as I can figure, it's just because they don't manufacture them in large numbers anymore, and there were a lot of newbie gun-buyers who wanted a gun, but weren't exactly knowledgeable about guns, so they just stuck with guns they saw in the movies. The Model 29 has been in a lot of movies, most notably Dirty Harry and Taxi Driver, in which they were hyped as "The most powerful handgun in the world" and shown/spoken of doing spectacular things like blasting men clear off their feet or otherwise blasting limbs clean off, which obviously would make them highly appee towards folks who are feeling particularly vulnerable.
That's my best guess anyway.
For me, the prospect of buying a S&W 629 has been suspended indefinitely because they're just not worth the inflated prices they're being sold for right now, not to me anyway. Every once in awhile a Performance Center model shows up at a decent price at or just slightly above MSRP, but so far I haven't been in the right place at the right time to get one. I can extremely close to buying a Used Performance Center 629 UDR a few months ago, but it sold a couple of days before the money was deposited, so I ended up buying an H&K USP45 Elite instead. No regrets, as that was another gun that I really wanted.
The best you can do is just shop around and wait until one goes on sale for a decent price. I recommend looking at Performance Center models in particular since they're priced more fairly.
