[Retro]

I have a rotophase converter in my shop, runs the lathe and milling machine etc. Depending on what else you might want to run it might be an option. 3 phase equipment is usually cheaper to buy. If you dont plan on using any 3 phase a single would work well too, I would overkill the compresser somewhat, it will run less and build air better. More is better than not enough in my opinion.
I bought my phase converter here http://www.americanrotary.com/products/phase-converters
Its a 15hp 11.2kw/240v