I doubt it could be repaired and used. the damage will extend beyond the crack and the areas surrounding that will now be work hardened and thus more prone to cracking again (plus the heat involved in welding this could work harden it further and create a heat affected zone).
If you can get it for a couple of quid it may be worth buying just for your trial fit - But I personally wouldn't be looking at a repair (I'm sure there will be those that may risk repairing that, and if it were a car wheel it may be a different story, but when you only have two points of contact with the road, I wouldnt want to mess about with either of them - pukka wheel or nothing for me!).