Coundn't you just tig weld the crack and polish it smooth?. Properly done, the tig weld would be the strongest point on the rim and a quick wheel balance would make up for any weight differences.I would talk to a professional welder and get a second opinion.
I have talked to a guy in Miami, and he said it will cost me around $80 or so, depending on the crack. But I am going to see if I can find a company locally that has an aluminum welder, and see if they can do it any cheaper, it shouldnt be too much of a task, I'm thinking around a half hour.