I think $125.00 is way high unless money doesn't matter to you. I've done a couple dozen action jobs, mostly for myself and friends, and the most I've ever charged was $20.00. I replace the springs if asked to, polish the innards, and test for reliability. Generally, the DA pulls drops from around 12-13 pounds to 9-10, single action isn't affected much, but the DA stroke is MUCH smoother. I learned it by getting a few books, and watching a guy tear his S&W M-19 down once. It's not complicated, takes very few tools, and can make a world of difference. Give it a try!
PJ the Tinkerer