that is steep. they won't make up a cent if it keeps even more people from coming in to their stores!
for that amount you can get the needed drill bits and still have bucks left towards a jig purchase. if you have an old pair to practice mounting on it's well worth going DIY. i was inspired to do my own mounts after one too many botchy mounts at a previously trusted shop. i've probably mounted a dozen pairs since and never botched one. it's easy.