Buy the Walker Enzyme refills. The very best, and very reasonably priced when you buy the refills. If you want cheap but still pretty good, I have about 20oz of the 32oz Disc Doctor cleaning fluid, yours for shipping. This is the concentrate, mix 2parts cleaner to 1 part water, so in other words this will make about a quart of cleaning solution.
It all depends on what you want. If you want them absolutely super duper clean, Walker. If you want them pretty clean, Disc Doctor. If you want a science project, keep reading, there's guys here I swear are the Walter White of record cleaning.