R.J.
I think it's a TERRIBLE idea to get him a scooter when he says he doesn't want a scooter, and no matter how on sale it is, it will be wasted money.
((Also, kids get hurt on those convertible ones way more than straight skateboards... because the don't learn how to balance correctly))
Get a good board. This is deck, trucks, and wheels. Ideally, let him pick it out from the skateshop, because the artwork gets important to the kids and the artwork is REALLY varied. Ditto, the wheels come in all sorts of colors. I KNEW my son would want light blue wheels... but you should have seen his face getting to choose the light. blue. wheels.
Google skate shops in your area, read the reviews for those that are kid friendly (about half LOVE kids, and the other half you don't want them anywhere near), and carry kid artwork boards (he won't need a child sized board at 7... kid sized boards are for toddlers, he'll need a full size board). Go into the shop yourself to scope it out, and talk to the stafff (My 7yo wants a board, etc., etc., etc.). Then bring your son in a few days later.
REMEMBER: The single most important thing about a board is the helmet.
Expect to spend about $100 on the board, and $50 on the helmet.
Safetywise you WANT to spend that much, because the el cheapo boards at walmart/target/etc are TOYS. They aren't built well, have lousy steering/balance, and they break.
A good board will last for 15-20 years. He'll want a new one in 8-10 years (new artwork), and then you either turn around and sell that one (because good boards LAST), or you hand it down to a cousin or friend, or you let him deconstruct it and use the board as shelves, and the trucks to save money on outfitting himself. Because by the time he's old enough for new artwork, he's old enough to buy it himself. ONE price for you, in your lifetime. Instead of buying a scooter, an el cheapo, and then finally a 'good' board.
((And if, for some reason he hates skating, a good board sells for the same price slightly used, as it would new. It sells for ALMOST the same price even VERY used. Like 75 instead of 100)