70k isn't much of a markup really, someone got a great deal IMO.
The gavel price was $73k. Add the buyer's commission of 10% or 7.3k, and the buyer paid $80.3k for the pair.
Don't forget the seller commission due B-J also. 8% of 73000 is $5,840.
Buyer pays $80,300
Barrett-Jackson keeps $13,140
Seller receives $67, 160
For the record, B-J apportioned the selling price $55,000 for the coupe and $25,300 for the convertible.
2006 Solstice NA #000741