The market on new product is self-regulating. People won't pay more that they are willing to pay. If they priced them at $1000, they'd probably sell 6, and the tooling costs would never be recovered. They need to sell them at a price expected to sell enough units to pay for tooling costs and to make a reasonable profit. And as only a small number of '69 Firebirds were built, and even fewer remain, and only a handful will need new tailpans, it's quite a gamble.
That's why a lot of parts are not reproduced, especially for '69 Firebird.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching