Via eBay, I paid $34.99, or less than $8.75/jack pad, for the "polished knob" ones pictured above. And, didn't incur any additional assembly "labor costs," or cost for whatever adhesive was used to glue the rubber stopper to the hockey puck. The puck solution is a great less expensive alterative for sure, but I wouldn't trust the help at a tire shop to align four hockey pucks correctly (as you would take the time to do at home) or to not cause more damage to your car when they tried to use them, by misaligning them on your car when raising 'da lift... You kind of need a solution that allows you to plug the hole in you car with a pad before raising a four point lift to the car, no? Tough to align four hockey pucks on a four point lift at the same time while getting the alignment right with your car. I guess if you had four people at the tire shop, one at each corner, it might be safer/doable.
EDIT: I would also think the solution needs to be one where the nipple/knob/nibs (polished, shiny or not) needs to be affixed well to the base pad to ensure the jack (and pad) don't slip/move when jacking the car - especially true if just using a floor jack on one wheel! Many of the Jack Pads for sale have this nipple/knob/nibs attached via screws, bolts or part of the one piece injection molded pad.