For under a hundred bucks 3 mm farmer johns will protect you. Not going to make an arguement for comfort but the ones made for paddling aren't bad and wearing polypropylene under it helps. Dry suits are necessary for winter conditions but they leak when you rip them, the seals at the neck and wrists can drive you nuts and and it's a bit of a chore to get them on and off. Don't worry too much, though, buy FJ's first, eventually you'll own all of it. 
