Try finding a Kel-Tec KSG for less than $400 over MSRP.
Increased production capacity, my Aunt Petunia... :-)
There are some models that are hard to find right now, but that usually gets better over time. There is nothing special about any of the standard firearms being manufactured today - and companies want to increase market share. The firearms are mostly manufactured by machines and in the current economic market it is very easy for firearms manufacturers to run a 3rd shift. If it is profitable enough, they will buy more machines and hire more workers.
If Obama goes after firearms (a distinct possibility) there will be a big bump until the dust settles. Remember though, he will have very little support for such a move within his own party.
That is just my .02 and your opinion may differ. I will still say the Mosin is a terrific investment at 100 bucks.