Seems the Sims 3 Store has added a page dedicated to letting users know how they can pay for their simpoints. Mobile has also been added (this is new to the US), and the PayPal option has returned. Paypal went MIA for a bit.
Just in case anyone has not seen this page in the store yet, you now have an idea of what payment options you have to purchase simpoints. (Click the image to be directed to the store page)