I've never seen a 240 volt compressor it a 1/2 HP motor 2 HP is common, and go on up as the capacity increases. A local business recently switched from multiple 2 HP 240 VAC 60 gallon compressors to a pair of 480 VAC three phase units with 120 gallon tanks that are set upi to run their entire production line from one unit. It was the old EDCO factory that Emerson closed a few years ago..
Cheaper? When did yo go over to the 'Do it any way but right' side?
It's not cheaper when the extra labor and increased material costs are added for doing the job more than once. If you didn't size the conduit for more wire, you'll have to rip it all out & start over.
Then there's the cost of a bribe to get the inspector to look the other way.