rabn21:
Would it be possible to use this power supply and use a voltage divider to reduce the voltage from 19V down to something like 8.4V using a 2.2 kilohms and a 1 kilohm resitor?
NO.
Voltage dividers are not suitable for power supplies. You need a proper electronic voltage regulator.
The simplest solutions are either
{A} buy a mains power supply that provides the voltage and current you need
or {B} make up a suitable battery pack using AA cells - re-chargeable NiMh cells can produce more current than alkaline cells. Perhaps even have separate battery packs for the different motors.
...R