Is it possibly to convert single phase to three phase to save money running motors. Or will the amp draw on the converter be more than than the single phase motor consumsion?

As general norm any electrical conversion has a maximum efficiency of 90%. The rest is converted to heat (total loss).
Besides that : a 100 Watt motor is a 100 Watt motor, no matter how you power it.
So whatever type of phasing you apply, the total power consumption of a motor will not decrease (although due to the higher voltage used in a three phase system the CURRENT will be lower). Going to three phase all you do is lose that additional 10 % input power to heat.
;)