www.miragetechnologies.netBest prices on EOtechs, period.
Now, in answer to your question, the NV version (550 series) has an Infrared projector in addition to the visible red one. The IR is only visible with NODs on. It costs more because it has that extra part.
A standard EOtech (510 series) will work with night vision.
But like Rick said, don't fret over it.
Also worth discussing is which model. Get the AA battery version based on battery life alone. Some people bitch about N cells, but they are available at any WalMart, drug store or hardware store. The fact is that N cells simply do not last as long.
The AA version is 512 for std. and 552 for NV compatible.
Stay away from the Bushnells. For the price you can get one from mirage, theres no need to sacrifice.
I'm calling to buy one right now!