A while ago someone was running stats on the TB classifieds, comparing average prices and such. Business school research paper or something. It would be interesting if he were to do a longitudinal look over five years' worth of ads or so and see if there really is any statistical change in the rate at which instruments are selling. Meanwhile I think this is all just subjective impressions. And of course, sometimes something sells, on TB or locally, but the seller never bothers to close the thread. They just stop bumping it and it sinks down the list as a seemingly unsold instrument.
My personal, purely subjective impression - nonsense. I actually was just thinking this morning, looking at multiple basses in the classifieds that I had found intriguing but that were gone before I could accumulate the savings to spring for them - "Wow, that went fast." Maybe it's just this moment, people spending their Christmas bonuses or something. But the bottom line is that instruments are pretty expensive, they're not necessities, and most people on the forum already have one (or five). Offering a $2500 bass for sale for $1500 may be an incredible deal but it doesn't put $1500 play money in my pocket and doesn't make me need a sixth bass. It's going to be a slow turnover market no matter how good the economy is.
On the local CL, there is a custom Taylor T3 that has been reposted and reposted for something like four years now. The seller wants $3500 for it. Every once in a while over the last year or so a custom bass shows up, fretless to the 12th fret and fretted above it - I think the asking price is $3850. Great instruments? Sure. Great prices? Probably. But who's going to buy them? Post an MIM jazz for $300 and it will be gone in a week.