There on eBay all the time. Just type in "1968 Firebird Promo" and you will find one. Expect to spend $200+ for a mint one. Looked today and saw a 1967 but no 68's.
really!? Those are the promo cars? I have one and never knew it. It's a 68 Meridian Turquoise one. It must have been from Dad's original Firebird. I played with it lots as a kid, so it's not in perfect shape, but we sit it in the rear window at car shows.
Wow they are really expensive, but I never knew they made them. I have 3 70's Corvette's that I've had since I was a kid. They only go for $10-$20 in the box.