I use square-up but there are other vendors as well such as intuit's go payments The nice thing about square is that there is no fixed monthly fee (but they charge slightly higher rates). I think you need to do the math on volume vs fee to see where the break-even point is for you.
I have just ordered the square reader! I love that there are no monthly fees! I don't have a wedding every month where the bride and groom wants to pay with the plastic.