if you look at the main 3G pic on the razer site, you can see the buttons/rockers built into the raised ridge along the side. The Diamondback built the buttons as part of that ridge, and they work like a rocker or a switch. The Copperhead has buttons just below the ridge. The Krait is a Diamondback without the side buttons.
The price difference is about $10 between the Diamondback and the Copperhead on Newegg, $20 on Razer's site. The Death Adder is $10 difference on both the Razer site and Newegg. The Death Adder changes the design a little.
The differences in sensitivity goes like this:
- Diamondback - 1800 DPI - infrared
- Copperhead - 2000 DPI - laser
- Death Adder - 1800 DPI - infrared
To see what ink would run you, go to WalMart. Look at what printer takes what cartridge, then look at the price of the cartridges. Every time I am in WalMart and see people looking at the printers I tell them this. To me, HP's replacement cartridges aren't bad. Lexmark used to be really expensive, same with Canon.