Taking TL's advice a step further, there are many, many BBQ Rubs out there and you might want to consider in addition to the info TL mentioned giving the customer a quick description of the flavor profile of your rub and what you feel it really does to meat when used properly. Information you might want to know about a rub you've never tried before you would spend your money.
In other words give him or her a reason to want to buy your product, as if free shipping wasn't enough =D>
, instead of just saying, oh another guy who thinks he knows how to make a rub.
Treasurer, Great Lakes BBQAssociation
Rubbed, Smoked, and Sauced Competition BBQ Team-
22 1/2" WSM, 2 18 1/2" WSM's, 22 1/2" Weber Kettle