Most loaded question of all! Welcome to TNet. Best thing to do first is post what you have decided to hunt for...nuggets, buried caches, battlefield relics, coins, lost jewelery, etc, then figure out where you plan to hunt...fresh water, salt water or beach, woods, desert, ghost town, or public parks and schools, etc. Different targets and different locations and conditions can require much different detectors. (Myself, I would go for a new entry level detector with your budget. I wouldn't trust a used detector for 150, especially if I were new to the hobby I would want something I was sure was operating properly, but that's just me, someone else should chime in soon.