Believe it or not, Hive Punks was created with zero costs.
The funny thing about the "create a NFT and put it on OpenSea" videos that I've seen is they barely talk about the cost of setting up an OpenSea account and then the Gas fees for those who purchase the NFTs. The one thing I like about Steem/Hive over others is not having the fee to do business.
When minting the NFT did you use a standardized template for the contract properties to show how the NFT was unique?
RE: My thoughts after selling 10,000 NFTs in 36 hours