DIY pumps are not that hard to build..just require care an lapping in to get the clearances to a minium. I have built around 4 pumps varying from 10 bar at 400ml /min9mod 1 9 teeth x.1" deep) to a 30 bar monster at over a litre /minute (eats current this one!) mod 1 gears 10 teeth x.25" deep at 3000 rpm. I did try an axial piston pump . The extra parts and complexity were not worth the increase in volumetric efficiency at this scale. A gear pump can be built in a day in a workshop with mill and lathe. You could do it with lathe only as my first pump was done.
