Rotary phase converters are simple to build, and cheap if you use used parts.
If you are going to rope start a 10 hp 3 phase motor very often, then be sure to set aside some money for new shirts. Your biceps are going to grow
I started off with a bare 5hp 3 phase motor, spin it up and flip the breaker on, if it wasn't spinning fat enough when I flipped the breaker on it would growl at me.
Used some stuff I had gotten in a box for $5 at an auction to build a self starting phase converter out of that same 5 hp motor. Works a treat, just flip on the breaker and away she goes. Got bored one day and built another one with big old meters to monitor voltage on each leg, never used it though.
The phase converter powers my mill and surface grinder, the lathe is powered by a VFD
I never bothered to balance the converter, it's a 5hp powering two 1 hp machines.
Oh yeah, a 10hp three phase motor is going to pull an awful lot of amps as inrush current when you start it, so you might think about using a 1/2 hp or so single phase motor with a belt and pulleys to spin it up. Leave the single phase motor hooked to the 3 phase motor permanently. Just shut the power off after the 3 phase is running. Won't hurt and it will actually help if you're starting a big load.
Practical Machinist has a whole forum on phase conversion.