You get what you pay for. Cheapest polypropylene caps I think are X2 filter caps. They're made with very thin metallization, to the point where their ESR is sensible just on a regular ESR tester (assuming test frequency is high enough to ignore the capacitance still). These kind are good for maybe a few hundred mA of AC current, before they're already getting uncomfortably hot.
Pulse rated caps aren't necessarily what you want. CDE 935C type caps are nice and low ESR, plenty of pulse rating, but they get hot at AC. They're only good for a few amperes at 100kHz. On the right track, but not actually the best option.
So it takes some shopping around to find a good family. If you don't see a voltage or current vs. frequency rating graph in the datasheet, it's probably no good. If you do, great, mark that down for comparison. (When you see V(F) curves, usually V drops off linearly with F, beyond some cutoff point; this is simply a constant current, because reactance. Take the slope to find current.)
Add up as many as you need, in parallel, and there you go.
That's what I did for my first one,
https://www.seventransistorlabs.com/tmoranwms/Elec_CapBank.htmlThink that was these,
https://www.digikey.com/product-detail/en/epcos-tdk/B32652A6104J000/495-1333-ND/592909 which seem to be more expensive than I remember, but it has been a while (gosh, nearing a decade I think). I thought those parts had disappeared, or at least fallen into the abyss (the "52 week lead time" one), but, hey, I guess they're still making them after all, neato.
There may be better amps/dollar out there today. That was just what I found back then.
Tim
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