Why are you buying it?  If you enjoy playing the game, do you enjoy it enough to pay $300+ to own it?  If you're buying it as an "investment" (e.g. you figure that you can sell it for more), I'd advise caution (you may find yourself the proud owner of a $300 cab which no-one wants).  There is a Spawn on ebay for US$550, but it looks like a conversion (two player CP).
Personally, I would also be wary of buying anything from a store which is going out of business. Tthe store may have debts or liabilities and the machine would be considered an asset.  Thus there may be a bank or even Uncle Sam who might argue the owner didn't have the right to sell the machine to you.