In my opinion, (which should be understood is not based on any great amount of electrical experience), there should be a way to accomplish this for reasonable money. If it were mine, and I was doing it for myself, I think I could come up with a system that would work reliably, and safely. There's certainly nothing wrong with using top of the line components, engineered for exactly this type of application. But I really believe that other options exist that would perform the same function for less $$$$
I simply don't believe that there are always, only two ways of doing things...the right way, and the cheap way. There is often a middle ground to be found with a little digging.
Safety first, always. You're dealing with electricity and water. But many items have dual functionality, or will perform well in applications never envisioned by their designer. Thinking outside the box has produced excellent results for me in the past...with a few failures to be sure.
Research and experiment. I would begin by verifying your pump specs.
