If you haven't tried it yet, you should really give Froogle a look. I'm currently looking to buy an LCD monitor and I checked the usual suspects, Pcworld and Tomshardware for reviews, Pricegrabber for prices, but due to lack of inertia, I never thought to try Froogle.
Searching Froogle, I found a Dell Ultrasharp 17" (highest rated by PCWorld) for $399.00 with free shipping. At that price, I think I'll get two. I was intending to get a 19", but since 17" give you the same resolution as a 19" and are much cheaper, I think two 17" beat one 19" in terms of value and productivity.
I'm also in the market for an ergonomic chair, but that could take a lot of research.