One of my buddies had a pretty bad experience buying used cusco coilovers. He bought it through a shop that got them straight from japan. However, the fronts were blown and he was stuck with those coilovers. He tried to see if there was anyone that could rebuild them, but as it turns out you can't rebuild cusco coilovers, since they are sealed. All you can do it send it to them and they'll send you a brand new pair for price of an arm and a leg, LOL
So just be careful with buying used coilovers, especially the ones you can't rebuild at a shop.
Also, that guy is selling those coilovers on a local 240 forum as well. So I guess he's just trying to see who's gonna give him the highest price.