Unfortunately, prices have been slipping over the years from peak.
My experience…Numbered edition sets gone for ~10k. Lettered editions ~25k.
*depending on completeness (chapbooks and things) and future rights.
Here are some sets that have sat for a while:
https://camelotbooks.com/clash-of-kings-a-storm-of-swords-a-feast-of-crows.html
I agree, FB group is a great place to check out.
Great set! Congrats.