The Mustang Walden buys is way under valued. Models like that go for way more in that state, usually starting around the $8,000/10,000 range.
Courtney Thorne-Smith and Kimberly Williams-Paisley played sisters on According to Jim.
Walden said that he found his car on a website called Dude Where's My Car. This is the tile of the 2000 film starring Ashton Kutcher.