Count me in as done with buying 3X products.
I remember when 2E came out...that was quite a different situation. I never actually bought a 2E PHB and kept using my 1E book for the whole time. Eventually one of my college buddies left the area and gave me his books as a gift. I didn't see the need for an update to 1E at the time, I guess.
When 3E came out, I was playing in this campaign that was heavily house-ruled, and we kept playing it for almost a year after 3E came out. After a while playing 3E it became almost painful to play in that game, and once that GM adopted the new rules no one looked back. Declarative Initiative? UGH!
So with 4E coming out, I see it having a real chance to fix some of the problems with 3X, especially since I use most of the WotC splat books and they have some horrible balance issues. I'm currently running a moderately high level game (12th level) and it is becoming more of a chore to run than something I actually enjoy.
I'm sure when 4E comes out I'll be in some strange hybrid world for a bit, but if it can fix the problems I have with higher level play, I'm not looking back.
In the mean time, I haven't picked up a WotC product since...August, I believe, and there's been no third party stuff since well before that, outside of a Pathfinder subscription that I picked up before knowing about 4E. On the other hand, I have picked up several books that have nothing to do with OGL/D20, so my money has been still going to some good homes.
--Steve