Where can I get custom patches (letters) for my high school letter jacket?

We've started a Quidditch Club at my high school (the sport that they play in Harry Potter) and people were wondering if they could letter in it, which is allowed at our school with clubs, so just wondering where I could get those made. The letter would be a picture of the golden snitch, very much like the one on the cover of Quidditch Through the Ages. Thanks! :]