ok I happen to have a blade they cost $750 new going price used is about $500 what deck does the mower have a manual or ele the price difference is quite a bit from $ 3000 to $4500 and size is also a factor also the 721 is really made for a 52 in model only not enough power to run a 61 with a bagging system, the blower works off you deck and you do feel of the blower pulling on the engine what is nice the blower can be removed so easy to make side discharge . you have not said year of mower or deck size or if used by home owner or business. very big factors in getting the best price with out a bagging system the mower will bring less money $1500 to $2500 less