A very nice pc, and a good price.
But, often a buyer will offer less because they do not like some specific part.
I might not like a large case with "bling"
Or a liquid cooler.
or.....
Often a pc will fetch more when separated into parts.
Go to ebay and find your expensive parts in used condition.
Then filter on completed auctions.
In green, you will see what your parts are worth.