There have been some problems with some of the "recycled" cartridges. People assume that what they get in the store is brand new, but more and more often it contains recycled parts, which the manufacturer's are supposed to make sure will keep working, but sometimes do not.
They're selling quality "knock-offs" for less than 50% of the regular price. Base charge for shipments is $5.95 and covers approximately 1.5 lbs. or less, depending upon the size of box required. So you really start saving money by buying more than one. I have bought 3 of the one I need for only $4 total over the cost of one in the store.