In CA it's just a matter of checking a box, then they put a transformer on the PG&E pole to match your voltage reqs - the wire to your pole is $90. The transformer can run in the thousands probably up to 10k.

That said you just pay that once, after that you have your rate.

A lot of people have odd power requirements - but usually not residences. Farms typically get 400V for greenhouse fans, for example.