I've noticed the same thing at Performance (which is the same company as Nashbar). Prices can fluctuate a lot and are often different in-store, online and in print (thought they'll give you the lowest price no matter which way you buy it if you ask). I was looking at a CX bike around Thanksgiving last year. It listed at $1,800 and was on sale for $1,000. I wasn't ready to buy so I just kept an eye on the pricing. Over the next couple of months, it bounced between $1,250 and $1,600 several times but never got back to $1,000.

I ended up buying a different CX bike (found out the online specs were wrong on the one I was looking at and it didn't have rack mounts I needed). The bike I ended up buying went on sale a month later and I got $100 + tax back with their 90 day price guarantee. Not sure if Nashbar offers the price guarantee.