Move character between accounts

No way to move characters across accounts (or across servers, for that matter) that I know of. So, yeah, start over.

If you have a guest pass to give, I'd suggest you give him that instead.

For now, guest passes are the best way to do this.

But in the future, Blizzard plans to allow you to sell characters across accounts:

We are also planning to allow players to buy and sell characters in the auction house at some point in the future and will have more details to share on that at a later date.

This is confirmed by the official Auction House FAQ and by Bashiok. See this answer for more details.

This may or may not be a good way to give a character to a certain person. Perhaps Blizzard will add a "private auction" to allow this. It never hurts to suggest it to them, either.