Yeah, the Ecotech are pricey for sure. They do come in different sizes and you can sometimes find them used for half retail.
However, there’s also these Hygger pumps for $70-$80 that looks pretty nice and seems to do a similar function. Never tried them but they might do the trick
Hygger Wavemaker with Controller
Hygger 3400gph DC pump
Black Friday sales prompted me to get one of the bar shaped ones from hygger. For the most part I think I was able to create what I wanted with this by turning it upside down (right side up it will only angle forward or down), pointing it upwards at like a 70 degree angle, and setting the wave frequency to the lowest setting. The waves still come out pretty fast but with how it's going the "waves" that reach the other side of the tank and wash back are a pretty reasonable frequency. Still messing with angles, placement heights of the thing itself, as well as the repetitive pulse vs random pulse.
I put a strip of paper towel (yes I know) to see how the flow affects it so I can compare that to the waving of anemone tentacles in the video I sent, to be sure I'm getting the effect I want. So far it's pretty good. Fish aren't impacted by it too much either. By pointing it up/a bit forwards I'm 1. Creating a wave that goes across the tank 2. Able to use the highest setting because that's not what the fish are actually swimming against. Going to try putting the thing higher so the fish can use more of that side of the tank. It's in the middle right now.