I finally decided to put my hands on Guild Wars 2 (played in BWE2, liked it very much). I got to https://buy.guildwars2.com/en/.
Oh, there're price drops and even more, deluxe edition's cost is reduced by "free upgrade" to 45$!
You click on Deluxe edition's Buy button. In the block "Order summary" you see:
Digital Deluxe Wizard Edition... $59.99 USD
Discount........................... -$15.00 USD
Total................................. $44.99 USD
Then you switch to paying with PayPal and discount magically dissapears! Even if you go back to "Pay with credit card", discount is still not there and your total sum is $59.99 USD.
This is obviously a bug so be careful not to spend extra 15$ because of it!
P.S. Didn't find where to submit bugs related to website's work. Any help?