I use Fantasy Football Plus!. I thinks it's $24.99 per team... But if you don't want to pay; they offer free Fantasy Football. It may not be as competetive, but it's jolly good fun. That's where I started out.
He already has an off-line league, so they wouldn't even need to separately buy teams. They could all chip in for a plus league, but if all they need is the ability to enter in an off-line draft, Yahoo's free fantasy football will work just fine.