My first try was an inexpensive roller pump and I paid about $100 for it. I got about 5 years out of it. When I had to replace it I paid about $170 for a little better one . It is still running well.
GWM,
If you go this route you will also need an adapter that goes between your pump and the PTO.
John is right about the spray tips not being dripless but I haven't found the dripping to be a big problem. I didn't have any issues adjusting tank pressure but maybe that is because I got the cheap roller pump.
Thanks,
Jack