in san diego...
https://www.aabikes.net/
in la, there was a guy with a cornucopia of a shop replete with bike parts, frames, wheelsets perched on the edge of the "sunset triangle" at the corner of edgecliff and griffith park drive
a block north of sunset in the silverlake area. open early (fixed a broken shifter cable in 15 minutes after i stopped by at 7:30am and repaired a riding companion's wheel a little after
8am about a year later) and was super-affordable. tipped him 3x his prices to fix both items both times. picked up a new tire from him at another point as well. rode past about two months ago and the building he was housed in is under construction
with no sight of his store. hoping he popped up somewhere else as he was a really nice and humble guy.