My purchases have slowed down but that has more to do with finances rather than desire. I do purchase as many 4e books as I can get, despite the fact my group is currently playing Pathfinder. I like Pathfinder, I truly like 4e, but I have to be careful what I spend my money on these days. For instance, I have no plans to purchase the Bestiary because I am experimenting with using 4e monsters in a 3e game. Essentially my players are using 3e characters and I am using modified 4e monsters. There is still a strong possibility that this campaign will be converted from Pathfinder to 4e some point in the future. This experiment will help that transition should it come.
I am a subscriber to Paizo's modules because they are usually pretty darn good and can be converted if necessary. I am not sure how long I will remain a subscriber. Definitely sticking around for the next three because of these two modules:
Carrion Hill:
http://paizo.com/store/paizo/pathfinder/pathfinderModules/pathfinderRPG/v5748btpy87df
Realm of the Fellknight Queen:
http://paizo.com/store/paizo/pathfinder/pathfinderModules/pathfinderRPG/v5748btpy87iy
I figure both would make great conversions.
I do buy some fluff products from Paizo, notably the monster revisited books and the planar books. For instance, the new book on the Nine Hells looks great.
Mostly though, I find myself purchasing a ton of props these days. I have lots of cardstock terrain, campaign coins, item cards, and other minis and props that help bring the sessions to life.
I do have to say that 4e re-ignited that creative bug and I am more inclined to design a campaign from scratch now than I was at the height of 3.5. I don't use a lot of pre-fab adventures unless I think they are truly amazing. Even then I usually just steal bits and pieces for inspiration. That has led to a slow down in its own way.
But I still find sourcebooks really appealing, even if I already have access to that material in the DDI. I guess I am something of a collector because I still purchase the occasional 3e book that I will never use.