Build me an ERC721 Smart Contract for my 10,000 NFTs

I have 10,000 NFTs that I’d like to deploy to the blockchain. I want a collection that is in opensea like all the others (Pudgy Penguins, BYAC, etc.) where they mint through my website and it appears in OpenSea after minting. I don’t know too much about the tech but the contract would be pretty simplistic my characters only have a few traits and there won’t be any breeding.

Please let me know the cost of this and the amount of time it will take.