try basement lighting in the u.k..it might save you a tenner.
but thats a great price man. you wont get a 600 any cheaper..is it duel spectrum(m/h+hps)? if so id grab it.. also check what size the reflector is... a friend of mine bought a 400w hps on line for £120 but the hood was very small and he can only grow 3 plants max..

also dont buy from ebay america even though the prices look fantastic. they work on a different voltage i think..happy hunting