You'll have to get quotes to find out which is less expensive today. It used to be cheaper to rework a stock crank but then the Chinese forgings changed that picture. But in the last 6 months the dollar has dropped, steel prices have doubled and the cost of shipping has gone way up. So in the near future new cranks are going to be twice as expensive as they were last year.

The era of cheap cranks is probably over in the near future. I'm expecting pretty big price increases to hit soon.