I would warn against using the pressure treated wood. On some treatment processes copper arsenic is used, which is poisonous. It sounds like for your price range that using cedar for the top and pine for the frame would work well. The cedar is naturally weather and rot resistant and will take the most abuse from the elements. Pine is a strong wood and the frame will be protected by the cedar. When choosing your boards make sure that the knots are "tight". If they are not they can fall out as the wood dries or while you are cutting a board.
I think the color combination of the cedar and pine will be quite attractive, monotone can be boring. Good luck and don't forget to post finished pics!
WSM, Green stainless Performer, Genesis 3000, 2 18.5" Weber kettles, CG Akorn
< BTW that's Hank.