All you have to do is look at how many parts it takes to make up a shaker setup and it will become quite clear why they are so expensive. Tooling costs are very high. Some dies will cost in excess of $100,000 and thats just for one of the parts. You have the baseplate, the ring, the gasket, the air cleaner lid, the air filter, the hot air and cold air doors, two cables, the bell crank, a left grille, a right grille, the diamond shaped retainers, the screws and the bubble. Thats a lot of stuff for $2800. At least now you have the choice of buying a repro hood. That saves a few hundred dollars over using the altered flat hoods. You can buy the cheap stuff and save a few hundred. Like the cheapo grilles being offered on ebay. If you don't mind bolting junk onto your car then it might be worth the savings. It's up to the individual to make that decision.
I have an original 71 340 base plate, ring and shaker bubble that I would let go for $2500 if anyones trying to restore an original car. The same parts in good repros would run around $1500.