I think with some of the after market kits the switches are small enough to fit on the plastic area around the bottom of the seat so there's no need for something out of place in a prominent position on the dash/console. A few of the guys on the Audi forum did this.
In terms of the OEM switches. I've seen quite a few on ebay over the last couple of months, usually around the £90 mark which I was told was too much. I also dare say that throwing out a search on one of the breakers sites would throw a couple up. Never a shortage of people wrecking Z's for us vultures.