If you're shopping for an affordable high output HPS system please check out HTG. You can get a 600watt HPS for a little under 300 when shipping is included. Ill link it for you

High Tech Garden Supply

youll have to custom out a lil bit but so yeah the 500$ for a 600w HPS sounds a lil beat, is someone middle-manning it or naw? I know Hyrdo farms or whatever are pricey as hell. Good luck &report back.