BBJ,
Wow, I didn't realize how expensive factory ammo had gotten. At first I thought $45/box was outrageous, until I looked at midway. Holy Schnikies $70+/box. I'd say buy the 180 partitions while you can at $45.
Although, these would peek my interest if I was in your shoes:
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=282522