Being it is aluminium to weld it it would need to be cleaned to bare metal, heated to remove any oils, set up the welding machine, preheat, weld out one side, grind the crack out from the back side, weld out that side to that you have a complete weld. Grind, polish back down so you could not tell the repair had been made. All in all it would take between 1 and 2 hours depending on how things go. Considering what would go into do a good job that is not that bad if a price.