I was building up my defenses for the 40 levels, so I was throwing a bunch of money out the door there at the end because I didn't know that things wrapped up at 39.

I'm just glad I beat the bastard!

 

You're right, it does end on 39; had 42 on the brain in anticipation of my next piece of "wood" (I love how it says you "get wood" every 7 levels)
Got 33,000 last time I tried. Had 13,000g in bank at start of Level 39, then blew it all on fire towers, finally selling them like mad as they were renderered overkill. I don't know how you can get through it without at least one elemental towerupgrade.
I can't stop playing...If food and sleep were optional, I would never stop. My computer keeps threatening to crap out though. I guess that's a good thing.