What forms of payment to you accept on your site? Eric Shanfelt September 20, 2016 23:14 Follow We currently accept Visa, Mastercard, Discover, and American Express, as well as Paypal. Have more questions? Submit a request Comments Martha Garcia November 23, 2014 01:15 I´m trying to may payment with PayPal but I get this error ¨PayPal Gateway has rejected request. Security header is not valid (#10002 Security error)¨ can you please help me I realy need to buy a book as soon as posible, thank you.