I agree, with you on part of that. Yes, pro shops are priced high on most items. However. You need to realize what goes into plugging and resurfacing.
Plugging.. you need to buy the plug mixture, plugging dams, plug cutter, sandpaper.. time.. etc. you and i don't know what plug costs/but look at you local bar.. same concept with beer.
Resurface.... they take LOTS of time and sandpaper and ball spinner... ok, or if they have a machine, they need to pay for the machine, diamond wheels, (cost to resharpen diamond wheels), buffing pads, etc...
the only reason pro shops charge so much for balls, is they need to keep reordering their inventory, obviously... these guys online simply drop ship the ball, so they have no overhead costs to deal with.
you get a more personal feeling when you deal with the pro shop, i think. He knows your other equipment, sees how it is drilled, and can accommodate you accordingly. He knows the bowling centers in the area and knows how the lanes react, and can sell a ball (or recommend one) based on other customers successes...
I can go on forever, but that just to name a few.
Again, I am not saying you are wrong, but here is my view on things