All the discounters are going to end up within $20/set with shipping, and usually within $5, so you're certainly not going to get burned. Which one will be the absolute lowest on a given day is a tossup, but I've had good results with the following:
Another vote for Jake Wilson:
Haven't ordered from Rocky Mountain ATV yet, but lots of people have. They sure do seem like a branch of Jake Wilson (nearly identical wording, policies, etc.), and sometimes offer slightly better prices.
Rocky Mountain ATV
An excellent vendor, with good prices. Always worth checking:
American Motorcycle Tire
Dennis Kirk has revised their tire pricing policies, so they are now often very close or the lowest. Plus, you can get other stuff on the same order for convenience. Make sure you factor in their dipshit $5/tire "fee". Also, they show actual inventory levels on their site, so if you just gotta have a tire fast, they're very handy:
And if you need an oddball size, or you're located near Dayton, OH, Tires Unlimited is always worth a look: