COUPONS FROM EBAY-WHY?

Lets face it your local store have a great deal in one product you use a lot and rarely see specials on it or just because you really like the product.In this case I gonna give you an everyday example:chesse.I use this product at least twice a week and we use a lot when making pizza.My jewel store get a deal a while ago for $1.50 ea great deal to buy 4 or 6 with the coupons I get on the sunday insert but that won't last for 2 or 3 weeks right?...
I decide to look on ebay...yes I found almost everything on that website that also is my part time job for sales..ok to the topic-I found 20coupons of 0.75off any *raft cheese for $1.50 FREE shipping.These coupons help me to buy 20 packages of cheese at 0.75ea=$15 OOP as a bonus the CATALINA machine give me back a coupon of 3.00OFF my next purchase at the store It's like a get all my cheese for only $12.00.