The last couple of cogs I've used are Dura Ace, Soma and the one I am using is Origin8. All of them have been extremely well, silent, reasonable wear-time, cheap.

I recently scored two Suntour cogs, 15t and 14t, both with Suntour NJS lockring for a grand total of $25. I have not used them yet as they are way too high for my application.