Add a Specialty Dealer to the game.
It would be an area where nee cars could be added in at special prices. Select regular cars could be cycled through at discount prices. And past reward cars could be cycled through for players who might have missed them or started the game later in the game lifecycle.
Could be a way of introducing the missed event cars back into the game 
Forza
Like they’re doing with the spotlight and VIP discounts?
They’d fit right in here too.
This. I think it would be great if all (past, current and permanent) reward cars would be cycled and priced accordingly to keep them still “special”. Prices could reflect the actual prices of those cars. For example Lexus LFA prices are from 700 000 to over a million nowadays.
I for one agree with you on needing real car prices
For years it’s been outof control people hoarding cars and selling them for astronomical price is sickening.
I checked the average market values for the four career mode reward cars.
Ford GT - 1 000 000
Lexus LFA - 897 000
Dodge Challenger SRT Demon - 138 900
Porsche 911 GT2 - 1 300 000
I think similar pricing would work pretty well in the game for reward cars (or all cars, really).
I agree with you