I got a custom dental appliance for like $1000 out of pocket, and it broke within a few months, conveniently when I had moved out of state from my original dentist.

There are a few over-the-counter options that advertise themselves as just for snoring reduction - SnoreRX and ZQuiet are ones I've tried. I've found that wearing a BreatheRight-type strip along with one of these appliances works as well or better than the one I got from my dentist, and it's MUCH cheaper. I also take an anti-allergy nasal spray, as I have pretty bad allergies also interfere with sleep.