Of course it's hard to say for sure, but when I was shopping over the last few months, there certainly seemed to be people buying. Sometimes the same trailer I wanted <_<
I guessing that maybe there are two forces more-or-less cancelling each other out:
1) The economy is in bad shape, so people are buying less.
2) The economy is in bad shape and gas is getting more and more expensive (generally), so people with much larger RVs and trailers are moving "down" to more economical rigs, so people are buying more small fiberglass campers.
I think it would be hard to say whether used prices were going down (unless someone is a real eagle eye and also knows what each sold unit actually sold for (vs. asking price), but if they are I don't think it's by much.
That said, my experience is in the sub-$5000 end of the market. Perhaps it's different for more expensive units.
Another thing to consider is that it is now winter in much of the US and Canada, so that will slow things down some regardless.