I get that barn finds are supposed to be super rare and cool finds. The problem with the current system is, that you can only have one of each of these cars. So in fact being a barn finds limits the usability of the cars.
For example: In FH4 i had 10 versions of the 2.7 911 RS, now i can only have one. Why would i what too have duplicates? Because this car has min. 3 tunable Versions: “RWB-Widebody”, “Standard” and “Rally-Safari” and i’d love to have all of them in my garage, but since it’s a barn find i can only have one.
I can’t buy more in the auction house because they are not sellable to prevent people to sell them an regret it afterwards.
My solution: Make them buyable in the autoshow and if you want to keep them special, make them expensive. I this case people would still be happy to get one for free and we would be able to use cool cars like the 2.7 RS to their full potential.