The cheapest way to get rims is befriend some cat that works at a rim shop. If they hook you up with a discount, you can't get cheaper rims on the net because of shipping.
Plus they normally will hook you up with free balancing, rotating, and switching back to your old rims in the winter months if necessary for as long as you own the rims.
I would also recommend going with a 3 piece rim, so in the event you curb that shit, you can just replace the barrel and not the whole rim, at like 1/5 of the cost of a new one.