I'm in Australia, and by Australian law pricing must not be misleading or deceptive, it must show all included taxes and charges.
IStock advertised that a particular subscription would cost $230 AUD. I spent 3 weeks choosing images. When I went to buy the subscription they charged an additional $23 in tax, and then I also found on my credit card over $5 in foreign exchange conversion fees. Unfortunately I needed to continue with the purchase as I had already committed time to finding the images I needed.
I have written to iStock twice to get them to refund the additional money, I have also spoken to them several times and they are not interested.
The Australian Competition and Consumer Commission agree that iStock is in breach of Australian law and I am currently taking up the matter with the Office of Fair Trading.
I suggest you don't deal with iStock as there are plenty of honest businesses out there you can work with.