Arymys, you can select "Specify amount of Crysta to add to your account" (the last option on the list) in order to type the exact amount you need/want. The reason I said pay with PayPal is because it still gives you an error if you try with a credit/debit card. But yeah the whole thing is on SE's end and it's complete BS that this hasn't been fixed after 2 weeks of complaints from various people.