Got to
www.autozone.com and put in your vehicle information. Being a worker at an express oil change garage who occasionally reccomends stuff at the counter, I suspect that they were asking $10.99 or 13.99 for it, and that you can get it at Auto Zone or Pep Boys for under $3.
The reason they push to sell you this stuff is because everyone in the store gets a bonus (salary kicked up for the week) if the store beats last year's sales numbers or car count for the week. Since car count isn't something that can be directly influenced by the employees, they have to push for high sales. If the receptionist reccommends package deals when you check in, he/she is getting a few bucks from each sale.