I had the same issue on my daughters Mazda 3...
Harbor Freight has a good kit for these
https://www.harborfreight.com/disc-brake-pad-and-caliper-service-tool-kit-11-piece-63264.html
Are there any good shops in SoCal, SGV area?
I just picked up a clean 2004 with 170k and would like to get someone who knows what's up to look it over.
Thanks!