I personally feel it would be worth the $50 just to watch them do EVERYTHING in that list of Merlin's. I have been riding on centuries when the RD [cable] had stretched enough that it didn't shift smooth anymore... and because I understood the behavior of the cabling, I was able to make an adjustment [on the down tube barrels] precisely and quickly while still riding to eliminate the problem. Also, lubing a chain should not cost money... nor should checking tires... perhaps the headset and chain wear, but other than that... watch em' do it, and copy them. [when you do it wrong just take it back in and have them fix it... and consider it tuition]