well, how used is the carb filter? they have a life expectency, how old are the bulbs? they have a life expectancy, if you get the ph tester, be sure to calibrate it. Looks like a pretty even trade to me considering you can buy a new 400w set up for about $300. much cheaper used on craigs list. IF the bulbs and carb filter are almost new. ok deal. If they need to be replaced. bad deal. IF all the parts that are not consumable in ok condition, (ballast, hood, and fan for carb) that would be about $400 worth of equipment new.