If you choose to cancel your order after paying the final invoice, you will be liable to a $500 restocking fee in addition  to being held liable to transaction fees. These are the cost of ACH/wire transfer, or the credit card payment processing fees.  Once a product has been shipped, or picked up, the order can no longer be "cancelled' and the Terms and Conditions of the Refund and Return policy will apply.  
Orders purchased utilizing a deposit / down payment to purchase them are also non-refundable transactions. Please see the complete Terms and Conditions for more information.