Now while whitelisting is the number one NFT collection marketing tool hands down, it is also very complicated technically to do it in the cost effective way
You see, before the Ethereum gas fees became so high, whitelisting could be done by simply submitting every whitelisted wallet address to the contract.
This method today is totally prohibited by the enormous gas fees you would have to endure. Using this the old method could easily cost you more than $50,000 to whitelist just 2,000 addresses.