this guy could be a complete computer newbie, suggesting for him to build his own could really be bad heh. here is one, it's open box but it has a gtx 460. if the motherboard has core unlocker that would be a big help, not sure if it does.
Open box typically means the product was returned for one reason or another. It may be missing peripherals such as keyboard and mouse. To quote Newegg directly on this: "Newegg only guarantees your receipt of the Open Box product with the purchase of this item. Any accessories MAY OR MAY NOT be included. Newegg will NOT send you any missing accessories, even if it is required to use all of the item's functions."