Interesting. If you buy early access to Path of Exile 2 through the official website then sales tax is include automatically in your purchase. So the $30 package is $30. Also, you can get a key for the Steam version after you purchase it through the official website:
Announcements - Path of Exile 2 Early Access FAQ - Forum - Path of Exile
Path of Exile is a free online-only action RPG under development by Grinding Gear Games in New Zealand.
www.pathofexile.com
If you have purchased a key and/or have access granted for one PC game client (Stand-alone, Steam, or Epic), but wish to play on another game client, you will be able to do so by claiming a key to unlock access to that client. These are available at my-account/early-access and can be redeemed on the relevant platform's store. Please note these keys only unlock the client in your library, they do not on their own provide early access to your account.
As an example, if you purchase a Supporter Pack through the Path of Exile website, you will be able to claim a key to unlock the client in your Steam Library.