Your 3x9 (3 chainrings x 9 speed cassette) setup was very solid and common back in the day, so nothing wrong there (I still have a 3x9 mountain bike). Your components are decent, so nothing wrong there. Before investing into parts, do the cheap things first, like adjustment of both derailleurs, lube chain, lube the shift cables that slide inside the housing, align the rear derailleur hangar. Try to do one thing at a time to pinpoint the issue. For example, if lubing the cables does wonders, you might want to consider new cable and housing. I'm not sure why your local shops want to charge a premium since the components and setup are nothing out of the ordinary. The little list of my to-dos can be done by any shop, Specialized or non-Specialized. The above idea of a co-op is a great idea.