Market price averages out at ~8K per piece. Not to mention 256x textures are most unpopular among textures. So it shouldn't come out to you as a surprise that 80-90K is the price most people are willing to pay, to buy a full 256x set. I would suggest you to sell it on market or someone who is willing to buy your overpriced textures. Thanks for visiting my shop though, please stop by if you have anything else to sell