When my kids were in high school, they bought some clothes in local thrift shops, the Salvation Army, Saver's, places like that. I formed the habit of walking through the stores with them occasionally, and even though they're deep into their 20s, I still check them out occasionally for bike stuff.
If you haven't considered that, it's worth a look. Some recent purchases or sightings:
--Brooks B-17, new in box, $4.50
--Dozens of jerseys, all kinds including some name brands, usually about $5.
--700C Mavic MA-40 rim (good wheel from the '90s) laced to Phil Wood hub, $15.
--Specialized Hard Rock mountain bike with Blackburn rack, Cateye computer, barely used (mold flash still on the tires), $10. I put road tires and fenders on it and my wife's using it as a commuter/beater. Old, lightly used mountain bikes are ubiquitous, usually for less than $40.
--KHS tandem, barcon shifters, decent shape, $450.
My favorite, sadly too small for me, was an old Dave Scott Ironman, the bike I coveted but couldn't afford in college, for $75. Didn't look like it needed anything but lube and tires.