I'm always looking and I don't see any price spikes in my area.
If you look on AR15.com in the sales exchange sub-fora, you can see that the market is pretty stable. Someone is always looking to make a killing, but deals can be had.
http://www.ar15.com/forums/b/7_.html
Ebay is another venue to look. The history of sold parts is a good gauge of market price. They can't sell completed uppers or lowers, but you get a real good selection of the basic needs for a build. (barrels, forearms, sights, ect...)
Another area I look is the Florida Gun Trader. (look to see if you have one for your state) FGT is nice, in that you see real local prices, and can sometimes make some real good purchases.
http://floridaguntrader.com/index.php?a=4
Additionally, My email has been flooded lately with "deals" from the different on-line sites. Most for parts.
My $00.000002