I've bought and sold allot of tanks in the last few years (more bought than sold), constantly changing my mind and/or upgrading but in my own experience, If you can get 25% of the retail value for good condition, used glass etc. you're doing pretty darn good. If it's worth more than that to you, you're better off keeping it for future use...until you've got ten+ empty tanks sitting in your basement with your wife constanly reminding you about them *sigh*
