What’s the value of this ??

I've sold core 4618 carbs for $500-1000, 4640's not so much...

Exactly. I’ve seen and owned many many 4640s over the years but 4618s are hard to find. I got completely lucky and found a correct 4618 with an intake, both dated correctly for my M-code GTS for 100 bucks locally about 5 years ago.