It's really just best to price around your available options, seeing what things will cost for your specific sales volume. For example, you don't want a merchant account with a $10 monthly fee if your monthly sales are $8.
Also, all of your options like credit cards, PayPal, Google Checkout,etc... can be reversed by the customer. That's not just a PayPal thing.
You might also want to correct your sig, since none of the promo codes can knock off more than $50 anymore.
Maximum savings promo code: MaxSavingsAtDH