Before investing tons of money, I would try Spin Clean Record Washer ($80) and wood glue method (Franklin International 5005 Titebond II Premium Wood Glue, $12 for 32oz, good for cleaning 100+ LPs).
For LPs looking clean but generating pops and other noises, I use wood glue.
For LPs looking seriously dirty, I first use Spin Clean and then wood glue.
2/3 of salvaged records (bought bulk from eBay and garage sales) turned out to be very listenable with these two methods. I also use roller cleaner (In the Groove Record Cleaner) each time before playing.
For LPs looking clean but generating pops and other noises, I use wood glue.
For LPs looking seriously dirty, I first use Spin Clean and then wood glue.
2/3 of salvaged records (bought bulk from eBay and garage sales) turned out to be very listenable with these two methods. I also use roller cleaner (In the Groove Record Cleaner) each time before playing.