Here are the prices I found for my printer (I only use black)
HP.com - $35.99
Staples - $41.49
Office Depot - $35.99 or $32.49 remanufactured
123Inkjets - $36.99 or $13.00 remanufactured
LDproducts - $33.99 or $12.00 remanufactured
Ebay - $5.98 remanufactured