I've noticed this too. I read somewhere once that designers capitalize on fall clothes and accessories because people will pay more for them then -- the textures (leather, wool) are more expensive to produce than the lighter summer stuff. I know that personally I am really drawn to the deeper, darker fall stuff when it first comes out.
Unfortunately there won't be a price drop later in the season for the biggies (LV, Chanel), but I suspect we'll see bags from the midrange designers like HH, Kooba, and Botkier start to go on sale around November, and then even more so in January.