Back in 2000 they used to say you needed 4 watts per a gallon to keep coral too and we now know that left a lot to be desired. Things like that are a very general and vague and often fail to take into account many other variables in the equation. Again, it comes down to "Do you want quality or do you just want quantity regarding flow/price" for your tank?
By the way I have a 20 gallon thats getting as much flow as your tank (which is 3 x bigger) Is using 2 x Koralia's and their wave maker, not because that was the best route to go but becuase its what I had that would give me the flow I needed until I could do some more research and come up with a better solution for my flow needs.