The Radeon HD 5870 Eyefinity 6 Edition card itself costs under $500. However, each of the six display will run you about $220 each, and setting up the system is a hassle. The results may be worth it, although the system that hold the monitors together can be a bit distracting, especially while gaming. Senior Editor Jason Cross gives you the tour.
ATI Radeon HD 5870 Eyefinity 6 Edition