I buy mine from Discountbowler.com.
They carry Pro Sports Contour Power, Turbo Quad, and Vise Oval grips
http://www.discountbowler.com/finger-inserts-s/1824.htmThey charge $1 each or 10 for $10. Yes, shipping is added.
Remember most places use either FEDEX or UPS, which have large minimal charges. If they were to also ship via USPS, it would a be a complication that most places can't afford in time and/or money.
Many places ship free when you get around $50. Most bowlers use accessories quite often and they usually need replacement on a regular basis. So just wait until you need enough to order the minimal for free. Otherwise, just make the purchase from your local pro shop.
I just order 10 each of the Turbo Classic clear to try them. $20 for 20 of them plus $9 shipping. Still cheaper that 90% of other places whose minimal price for a insert is $1.50 - $2 EACH, plus shipping!
