It's hard to get a bigger bang for your buck than you did. How did you know that there were Polk/Kicker speakers? Did you have to check it out yourself or did the employee there tell you?
Yup.....total cost for the speaker upgrade was $12. I paid 10 bucks for four speakers plus $2 entry fee to get into the salvage yard.
When I need a pert from the salvage yard, I first find my part then I look for fresh rows of cars/trucks. If I see a fresh row, I will snoop around those vehicles looking for any aftermarket parts on them: Stuff like: coil over suspensions, stereo amps, "racing" seats, FlowMaster exhaust systems, LED light kits......basically anything aftermarket that I can resell for a profit.
Best salvage yard things I've found so far has been:
A complete 4x4 Nitrogen gas suspension/lift kit for Ford truck.
A Jackson Supercharger for a Honda.
Verticle lift "Lambo" style door hinges for a Monte Carlo SS
Complete rear "Lowrider" style hydraulics system with "Powerball" pivot cylinders, minus the batteries.
Basically, when I found the speakers, I was car hoping the junk yard and got lucky.