i have the opportunity to get a nother 135 gal tank by itself,just the glass. 72x18x24. the guy says best offer. the tank leaks when half full but only needs some silicone he says. im going to see it tommorow and want to get it as cheap as possible. a 135 gal tank by itself new here is around $600 and have to be ordered in. so what should i offer him and what are some points i can bring up to get him to take a low price/ the add is 3 months old and looks like he's not a fishkeeper as he didnt know the size(135gal) he only knew the dimensions.....so??????