Genuine Hot Rod had an exclusive NHRA set last year. One of the cars only came in that set. They now have another run if the sets in stock.
The Johnny Gray car is a new Special Edition so far only seen on that web
I get their catalogs frequently and there is a drag set from Auto World and individual cars offered at the same prices as Auto World charges. perhaps one or more of the cars is exclusive and not available through Auto World. check the link in post #1 and give it some thought.
The Summit set is a special set much like the Matco, NTS, SNap On etc. It features the 2 Summit pro stock cars, Greg Anderson and Jason Line, and is the only place to get the Line car. The Johnny Gray car was released after the NTS set last year. I bought one about 4 months ago on ebay, that was the first I saw of them.