First, there are 6x6 and 6x4.5 folders out there. Including rangefinder models.
I don't understand what happened in the last few months, but TLR prices have gone up. Right now there is an Autocord on Ebay with a bent lens panel, which is a serious problem on an Autocord. It is at $91 with 4 days to go. There are at least two people out there who don't know their cameras and with too much money.
I consider the Autocord a solid step up form the Yashica-Mat. Its build quality is higher all around. Now a well-aligned Yashica-Mat will do very well, but the Autocord's Rokkor lens is better. The focus helix, once the grease is cleaned out and replaced, is much more solid and stable than the Yashica-Mat's rails. Here's a set showing the hellix system, with a couple of shots of a Yashica's rails.
http://www.flickr.com/photos/18067251@N04/sets/72157626869741228/
I know which one I'd want in a bag on my bicycle. I'd consider a Yashica at 2/3 the cost of an Autocord to be comparable.
That shop's price is very reasonable for this point in time. With a warranty, etc., they are being fair. Not generous, not a great deal, but fair. As to whether you want to pay, that's a whole other conversation.
Oh, Autocords were made for 10 years or more with many small variations. I have a thing for 10-bladed apertures so I prefer the older models (Optiper and Seikosha shutters, although there is an Optiper model after the Seikosha where I do not know the number of aperture blades). But the later Citizen shutter models, with Minolta Rokkor rather than Chiyoko Rokkor (same lens), get higher prices.
Avoid the 'L' model with the selenium meter unless everything else is perfect and the price is right. The meter will be dead, is a custom system that is annoying to use, and mainly just makes the camera bulkier.
Do the typical checks- shutter speeds, etc. The focus lever should be smooth. Depending on the grease used, it will have varying drag, but it should be smooth and able to be moved with one finger (I love the focus system on the Autocord, smooth and fast in the field). Winding lever should be smooth and relaxed. There is usually a small 'hitch' in the winding motion as the cam finishes the shutter cocking swing, but this should be simply felt, not need much increase of pressure to overcome.