I think LFS owners should "give" tanks out for free, up to a certain size. Let's say 20 gallons or so. Heck maybe even larger if they can.
Market that, sell filters/fish at regular prices, maybe hide in some things to make up for the tanks perhaps, up to you.
Your trying to model your revenue off recurring customers. The more excuses you give for them to be in their buying things the better your going to be off. Huge problem is people run out of tank/stock room so they stop buying fish/supplies on a fast paced regular basis, there is just no need/reason to etc.
hehe