Larry,
Sorry you cannot use a VFD on single phase motors. Now, you could use single phase input, but it would output 3 phase.
50hz is no issue. VFD's can operate on either 50 or 60 hz.
You just need a three phase motor and single phase supply.
Note: VFD's over 5hp require that you derate the VFD in single phase applications. 5hp and lower it's a non issue. ( most manufacturers)
Check
www.automationdirect www.baldor.com www.kb-controls.com (best for small VFD's)
for the VFD.
Check Grainger, Baldor or Weg for the motor. Weg is less money with fantastic quality. Made in Brazil
3 phase motors are less money than single phase.