Some LF items are in very low supply, for example 5x7 holders and various lenses that cover 5x7 and up. Replacement bellows are also in low supply. And LF lenses are probably not going to get cheaper, with Nikon out of the business, Fujis now quite rare, and other manufacturers turning their attention to lenses with smaller circles optimized for digital. The market used to be flush with low-cost brass lenses but that seems to have changed and many are now in the hands of 8x10 and ULF people who cherish them.
So... I'd say the LF prices (at least 5x7 and up) have bottomed out and are roughly where they should be according to supply and demand. Do check the cost of new LF gear though, e.g. from Shen Hao, I think you will be pleasantly surprised.
KEH seems to have inventory they want to move ASAP- their prices have been moving lower for several months now, including just about all formats. RE: ebay, when you consider the paypal payment holding policy and their fees etc. (which I b*tched about in another thread!) KEH is indeed a better deal in many cases. But try the APUG classifieds too!
MF prices are in constant decline, for several reasons. One is that new gear is still being produced, and there is actually a lot of new innovation coming through the pipes, e.g. cross-platform cameras. Plus small format digital, which has reached a certain, much anticipated, hard limit that I guess we won't discuss here, is applying some pressure. Plus I'd argue that MF gear prices were artificially inflated in recent times- the cost of some MF gear has never made that much sense to me, but I am not going to mention specific brands and start a brand war!