+15V and -15V from a 24VDC Power Supply
We use a couple switchmode converters based on LTC chips to get +/-15V for the 640 version of this MKS thing. Lots of components. 

If you're not making a circuit board you might want to buy a suitable DC-DC converter module with dual outputs. You could also use two 24V:15V isolated converters and wire the outputs appropriately. 

By the way, although I think the data sheet says 200mA, I think in practice one supply uses a lot more current than the other (to operate the coil in the proportional valve). The current draw on that supply varies greatly as the valve opens up- the other supply is just for the op-amps in the signal conditioning and (analog) PID controller.