Too much work to recall it all but a few stand out.
Early 80's, ADS aluminum cabinet mini car audio speakers, $8. They felt way to heavy, opened them up, filled with sand! Cleaned them out, upgraded caps and resistors, offered $500 for them a week later at local audiophile shop. I still have them, used in several different garages and shops for decades.
A couple of years later a little passive subwoofer with crossover, used with the ADS and good car audio head units as above. I still have it as well but do not remember brand.
ST70 in very good condition for $25 at the Navy base thrift store, refurbished it, used a few years, sold a couple of years later for $500
Mostly into car audio for a long time at a level many believe impossible to achieve but I can setup an incredible system far less costly and less work than a home system. Lots of deals, including sponsorship when competing, best speakers were Rainbow Reference, retail was $7k, I paid $4500 which was below what the distributor paid for them.
Everything I own now was bought wholesale or used at great prices though getting back into DIY speakers, I used to build quite a few.
I do have some little KEF line arrays I got for around $300 I really like with a decent sub, going to sell as no place to use them.
Best current deal was Martin Logan Vision X sound bar, dang fine and perfect for our full time RVing remodel until I get a proper system setup in it, $225.
