yep PSN sucks, i guess that's how they can make up for having a free service though. xbox live doesnt charge tax on downloads or anything like that.
that being said, ask somone with a credit card to buy it for you and give them cash. i love PSN but i have to say the whole charging tax thing is really lame on they're part. luckily i have a mastercard and dont need to worry about the PSN cards.