At the LBS I frequent they have promotions throughout the year. When I bought my bike in March it was during their "no sales tax on bikes event" and I ended up saving $40. I've established a relationship with this shop and when I make a big purchase (like when I bought a wheelset) I get 10% off on every item I purchase. On everyday small purchases, there's no discount and nor do I expect one.
In July all road bikes were 50% off in honor of the TDF.
August-Sept there was no sales tax on bikes and the prices on the 2006 models dropped significantly, but they filled up with 2007 bikes so fast I saw very, very few 2006 bikes when their liquidation event started.