I think a big part of it is the fact that Comic Con just happened, and the U.S. JoeCon is about to happen.
I'm positive the demand is still there for these. It's just that people are using their money for other con items right now - and summer.
Obviously the sets are not in that big a demand, so feel free to send me your sets and I'll make sure they get a good home!!

I think that Mike is partially right. I also think that summer time is a big lull with people spending money on vacations and upcoming bills (back to school, etc). Also, refund cheques are long gone now so splurging on extras is on the downslide.
I would watch more closely near Christmas when someone needs a killer present for their mate/friend/whatever.