My 8-year-old daughter still wets the bed regularly. Our approach has been to just let it be and trust our pediatrician (and everything else I read) that she will indeed grow out of it on her own. In recent weeks it's gone from an every night event to only about half of the time now, which I can only attribute to her getting older, as we've done nothing differently. By frequently assuring her that it's simply that her body likes to sleep more deeply than others, and that she will eventually outgrow this, she doesn't have big hang ups about it. In fact, her best buddy who sleeps over at our house often, knows that she wears a pull-up. Something like 1 in 10 kids wets the bed until age 12! So perhaps the less pressure, the better. Getting up that often all night long can't be good for you or your son. I would suggest doing nothing for a few months, buy the night-time pull-ups for big kids, and give your son's body some time to catch up with himself.
(That said, I might try that other mom's suggestion about drinking loads of water, just to see if it works. We make a joke of it at our house anyway, so I can present it to my daughter as a fun science experiment. She sleeps so incredibly soundly that I'll be very impressed if something like this does the trick!)
No matter what, just reassure your son that he is one of many, many children his age and older who wet the bed.