I swear by this one, and they are currently running a buy one get one free offer ($80 USD): Good Bye Snore.  I have apnea, but no insurance.  I can't afford a CPAP.  This has stopped my snoring almost completely, and I feel much more rested than I used to.  I wouldn't suggest this as a replacement for sleep testing and a CPAP, but if you are in my shoes it is definitely a viable option.  The best part, so far as I can see, is that it not only stops the snoring, but it also retrains your jaw so as to eliminate part of the cause of the problem.  The site I linked two has the study information posted, along with several other informative articles.