it costs 80 bux, so not really economical in the least. theres a review of it on techpowerup, but the cost of the 3850 + that cooler would basically equal the cost of a g92 gts, so if u can afford the 80 dollar cooler u might as well upgrade to the g92 gts instead.
This cooler is indeed closer to $80 if you have to buy the Ram heatsink plate that is required for some cards. However for a 3850 I don't think you need one. I own this cooler but I have it on my 8800 series card (along with the heatsink plate). It works very well, especially considering how hot these cards get. I also have my card overclocked quite a bit.
This cooler will never be on newegg as far as I know. They just don't carry it. I got mine from a separate site.
Just in case you didn't know, zalman just came out with an improved version of this cooler.
Basically the same thing (except in black) but the fan on this one spins a little faster I believe. I would have gotten this one but it wasn't out when I bought it originally.