Well, you've got it advertised in the right place (APUG and LFF). I think the price is reasonable - not fire sale but very reasonable. If it is a 45DX, you're asking 1/2 (or less) of the new price.

I don't know if the back is original to the camera or not, but certainly is a Wista back. In fact, it looks like it may be the back from a Wista technical 4x5 and, if so, an upgrade to the original back. If you have specifics on the back, I'd include that in the ad. For example, is it a revolving back?

Location could be an issue and/or, as Ian suggests, unlucky timing.

My only suggestions are to be very specific in your ad about condition of wood, GG, bellows, fittings, etc. I'd also put a lot of detailed photos up on Picassa, Flickr, or some other image hosting service. Let people see just how nice it is.