You can save a lot more if you replace them yourself.
If you use Contour Power (Pro Sports), Vise-Grip or Turbo Quad inserts, this place sells them for $1 each. I've done business with them for many years and they are reliable. Shipping is extra, so it pays to get some other accessories at the same time.
http://www.discountbowler.com/finger-inserts-s/1824.htm
Thanks for the tip. I assume that the finger insert will have the size somewhere on it. So when you remove it, you will know what size to order. What kind of glue do you use? The Pro Shop on this website offers Turbo insert glue for $15.00, but I am guessing that there are generic super glues that are just as effective.
Yes, they all have the size on them. You should use the same brand to keep the right size. For example, I use Contour Power grips in 25/32" and 3/4" BUT if I use Vise-Grips, as I do sometimes, I need to order 49/64" and 47/64", 1/64" smaller than Contour, because the Vise-Grips are slightly larger for the same size.
Normally I use LocTite Super Glue gel formula; I get it from Home Depot or Lowe's. Gel is much easier to measure out one drop. I use one drop on each side of the grip; that holds them in place forever. I use a 1/8" slotted screwdriver to pry them loose, when I replace them. (I use the same screwdriver to insert tape in the thumb hole.)