I finally bought a complete set recently. It just came in the mail yesterday. 14 CDs. I got it for $60. This seems like a good deal, since most complete sets are over $200.
This is the 1966/67 Böhm recording with Bayreuth, published by Philips. It's a live performance, so you can sometimes hear a couple ambient sounds of coughing or whatever. At least I noticed it when I was listening to the opening of Das Rheingold in the car yesterday.