1. The Nikon 10-24 is a half to full stop slower, however the 12-24 DX is a fixed f/4 (vs. 2. but just as spendy and loses mm on the low end.
2. It's more like $300 comparing apples to apples (new to new, non gray market).
3. $300 is not an insignificant figure in my photo life.
4. Telling the wife I just bought a $900 lens is not an option, period.
Bottom line, if either would get within a sniff of $400 I'd hit it so fast it wouldn't know what happened. Yes Jacob, prices are definitely inconvenient.