I live in Arizona, USA. I was thinking about buying one or two $20 Battle.net gift cards to buy the Karazhan adventure and some card packs. But, having searched all over the internet, it seems that because of the state I live in, I have to pay tax on in-game items such as card packs and adventures. Is this true? If I buy two $20 gift cards will I be able to buy $40 worth of adventures and packs or will I only be able to buy around $35-37 worth of items because of tax?
Blizzard specifies that taxes are applicable to your state (Arizona) as well as 14 other sates of America.
For questions or concerns about these taxes or your specific tax rate, contact your state’s Department of Revenue.
Also, if you buy 2 x $20 gift cards, you will be able to buy $40 worth in-game content no matter what happens.
Legally, you are not buying ingame items. You are buying the cards.
The purchase happens when you pay with real, US money to buy some "blizzard money". Blizzard is not a bank and those "blizzard money" are not real money. As far as law is concerned, they are goods. Let's call them "points" here to avoid confusion. They're not dollars, real dollars work everywhere, points don't. Once you've bought the points (by purchasing cards or online with a credit card), the US dollars changed hands, and it THIS transaction that's taxed. Neither Uncle Sam nor Blizzard care if you ever exchange those points into actual ingame items. They are happy because they've already got your real dollars and they're not giving them back without a fight.
So, when you buy $20 worth of points on Blizzard website, you'll pay $21.12 and when you buy a $20 card at convenience store, you'll pay $21.12 at the register.
When buying cards you need to keep in mind that Blizz sells them in bulk for lower price than $20, so the store can sell them for $20 and still make some profit. There are vendors who accept smaller profit and sell them below their face value. So it is possible that a particular vendor actually sells them for $18.93 which after tax will give exactly $20.