The Aquajet pumps seem to be available only through the distributors that serve RV dealers. Here are two websites that offer them:
I know nothing of either company, but the pump is around $145 either way. I found mine through another distributor whose name escapes me, but the price was about the same.
I went with the Auquajet ES as it has a lower maximum amp draw than any other variable speed pump, and was not therefore likely to overload the existing wiring. It works very well, easily supplying two faucets or the shower and a faucet with almost no noticable change in flow.
The one problem that showed up was rather a lot of water hammer from plumbing which was in contact with panels or the floor. The old Sureflo had such low pressure that it never caused this. I have had to wrap rather a lot of the plumbing in insulating foam to keep it quiet.