I know that I breastfed my children only until age 1, because after that I couldn't bear the thought of them "needing" that sort of comfort, asking for it, and me refusing it. <snip> I want the things that bring them comfort to be okay as long as they need them (a blankie, nightlight, prayers before bed). [\quote]
Except if it's something *you* don't want them to have, then they can't have it. Not trying to be picky, you're just a little contradictory here.
Anyway, back to the OP - my kids are 4 and 5 and still like to come to bed with us. I skipped the bassinet, crib and toddler bed and saved my money and got them a regular bed, LOL, so they went from co-sleeping to their own bed. My oldest transitioned to a mattress on the floor by our bed, then to her own room. My youngest went from our bed to sleeping with his sister to his own bed. I don't know about using the reward system - because you might have to keep upping the reward. Barbara Coloroso's book "Kids Are Worth It" has a lot of great advice - don't reward for something you wouldn't want to be rewarded for doing. And I wouldn't ground from the computer, as sleeping issues and computers are not related. You say your DH is a terrible sleeper too, so I can't see punishing (I wince to even use that word) your DS for something that may be an inherited trait and he can't help. It will only make him feel worse.
My 5yo sometimes has bad dreams, so we got her a dreamcatcher and a little "dream fairy" doll to take the bad dreams away. If she comes into our bed, I get up and walk or carry her back to her bed. We have a king size, but DD either splays out or gets so close to me or DH she's on top of us.
I would just keep walking your DS back to his bed, and help him to learn to soothe himself back to sleep while staying in his bed (since you can't sleep with him in your bed, and he is a poor sleeper like his dad). Maybe keep a favorite book and a snack by his bed, and he can do that for a few minutes while getting himself back to sleep (and staying put, LOL). Or set up a sleeping bag on the floor in your room.
Good luck!