Look honestly if you are looking for a 6x6 TLR the YashicaMats, and the Autocords have become a little pricey because of all the hype surrounding them. I would not pay more then $75-80 for a YashicaMat 124, or 124G or plain YashicaMat. I also would not pay more then $100 for a Minolta Autocord, or a Richoflex. Your best bet is a Rollie. For a little more then the cameras aforementioned you can buy a rolliecord. For less then $200 you can usually get a Rollieflex. This is the camera that all the Yashicas, Lubitals, Autocords, richos, etc, etc were made to imitate. The rollies are of a better build quality and have better lenses, esspecially if you purchase one with a Zeiss Planer, or Tessar lense. The winding mechanism in the rollies is far superior to the YashicaMats, which can be a real problem with some used cameras. If you do go with a Rollie make sure it has a PC connection for flash sync. Unless you are not interested in flash photography. I love TLR's but really its pretty much Rollie, Mamaya, then a bit of a drop off to the Autocord. The yashicas can make great pictures, but they are just not as well built, and when you are buying a thirty plus year old camera that matters.
Just an honest opinion,