If you're doing mech the best way to go is probably Zazzle, or possibly Redbubble.
Was also going to say that for payment methods it behooves you to have several as there are more common payment methods in other parts of the world that are easier for other people to use. Look at GOG for example...."We currently support the following payment methods: credit cards, PayPal, paysafecard, SOFORT, Giropay, webmoney, iDeal, Skrill, Alipay, UnionPay, WeChat, and Przelewy24. We also support payments via BoaCompra with a bank transfer, boleto, credit card, real-time online banking and wallet."
Interac E-transfers sound safe, easy, and cheap for NA users at any rate.
"You have enemies? Good. That means you’ve stood up for something, sometime in your life."