If you check the "For Sale and Group Buys" section on the home page (bottom) you can get an idea as to how much people are asking for their stock wheels and tires. I'm not certain on the list price but I would imagine they are worth about 1/2 (probably $1500 or so?). If you price them out, don't forget to price the sensors--approx. $75-$100 each.
08 S5, Ibis White w/Tuscan Brown, loaded.