Beating a dead horse here it seems, not sure I understand why 3 phase costs more from the utility, usually the main power monthly costs are per kw used, 3 phase has no other real downside, if OP ever finds a use for it, like with a "real" compressor, lathe, mill, etc it will be a real plus if functional, all other normal "single phase" equipment can usually run off of a 3 phase system, and if hell bent on downsizing the existing wiring, ditch the single phase distribution. My leaning towards the 3 phase here is assuming its a 120/208V 3 phase, if a higher voltage system, never mind.