Pricing depends on your locale and the demand both nationally and within the area. From what I've seen in the Gun List, their asking price seems normal.
In my opinion, the Diamondback .22 is the best .22 LR revolver to have. The action is based on the Colt Python and once properly tuned, it will stay tuned for a long time. The problem is, if you've been following the Colt made by Morons Thread here is that it is becoming increasingly difficult to find a revolver smith who knows how to work on Python/Diamondback type actions. Parts are more expensive too, but since they're 4140 steel, you replace them very infrequently. That set aside, I'd buy the Diamondback. If you enjoy plinking with a .22, I don't think you'll find another .22 which will give you as much shooting pleasure.
If you're into the woods and low maintenance, I'd consider a Ruger SP101 .22. Nobody makes a revolver as tough as Ruger. Trigger pull is not nearly as nice as the Diamondback or the S&W though. Another favorite of mine is the 8 shot S&W Airweight .22 with 3" barrel and adjustable sights. I'd go with that Airweight over the regular steel frame 6 shot S&W.
Enough rambling...happy shooting.
------------------
Vigilantibus et non dormientibus jura subveniunt