Lol
My ro/di was cheap on chewy.com my lights very from hi end to low end. Used has only filled my closet with outdated equipment but I can say save the money and buy what you want not what someone else had. A happy reef starts with a happy reefer.For your budget, buy used. You will be way more complete in your set up, with better quality gear if you buy used. Unless you're aiming for a 10 gallon or less, $500 won't cut it for a respectable set up. New RO/DI is pushing $200 alone. A decent light is around the same. Add in rocks, pumps, livestock, and you're bust.