I was looking for a good rc car under $350 that will do the best in the sand dunes. I was thinking a rustler vxl 3s and paddles. Are there any other good combos under $350 that is good for the dunes?

You don't need a whole lot of power for sand, I use a losi desert truck with paddles on the rear and splined front tires.

any platform will work, but i see you live in WA. you do get snow up there right? well then you may want to look into 4wd cars since 2wd will do nothing in the snow. if it is too slow, you can always just upgrade the motor to the vxl.
also have you seen the traxxas slash 4x4. i'm thinking this will be perfect for you since it is fast, can handle sand, and is 4wd. but they don't come out till.....December or later

See my bandit to Baja Bug build a couple of threads down. I'm building it to be a beach runner and I have less than $110 in it.