How much would it cost to change my manual doors to power doors ?

i recently bought a 06 cobalt LS. It came with manual doors, windows, and mirrors. the mirrors doesn't dont bother me but how much would it cost me to change it to power? would it be best to get it from a chevy dealer or some sort of aftermarket one.. even if i just somehow got key less entry it would be fine. any ideas ?How much would it cost to change my manual doors to power doors ?About the price of another car.How much would it cost to change my manual doors to power doors ?Why didn't you just get the Cobalt LS with power doors? Would have been cheaper.