I used two of the Easyeverything Cafes in AMS when I was there in December. The one in the train station required a 5NLG purchase and always seemed to be pretty busy. There is another one just kittycorner from the flowermarket that only required a 2.5NLG ticket. I was there at about 5am and was getting 288 minutes for my 2.5 guilder (about one US dollar) The most expensive I saw was the when the train station cafe had 77 minutes for the 5 Guilder ticket.