I already closed it so I can't show you, I had lasers all the way up the wall, solid guns on the ceiling,and a sold row of saws in the middle. The shells get trapped up top, so you get infinite combos. I hit a 2.5 million with that method, and level 100 valves.
I jumped from 350-400 hits to almost 300,000 right now
I beat it.
Your money sucks. And also, the turrets and saws are the best things to get.