maybe 75-100... prob is with tanks of any size is that they require pickup or high shipping costs... so when you have a tank that even if it was in a retail store, would cost about $200 or more new you are now limited to a small audience of people that must be willing to purchase your specific setup at a specific time. Some people like to say $1-2 a gallon is a nice price but I find that not to be so for all applications especially smaller ones like yours. It makes large tanks far too cheap and really small tanks too expensive (ie no one will pay $40 for a used 20 long and no one should ask $500 for a used 250g). A hex is a more desirable design in smaller tanks in my opinion so I think a really nice oak stand (not laminate and pressboard) and a clean tank with lighting (although the lighting is most likely worthless to most people) should be able to fetch 75-100 locally but probably closer to $75.
