Some etsy.com vendors will do custom orders. Might be worth it to ask around some of the "stores" that offer pre-cuts to see if they would allow you to send them your fabric to be cut into the desired shape.
You also might check around in your area. Ask at your local LQS & quilting guilds to see if there might be someone that would be willing to either sell you a bit of time on their machine or barter with you. I know there is a lady not too far from where I live that has a die cut machine & hundreds of die cuts. Last I checked, she let people come in & pick out the die & then charged them by the piece to cut it using their own fabric. Only thing you have to be careful about with that is most of the time they do that for paper & I have to wonder if the blades would dull (like scissors or rotary blades) if they've been used a bunch on paper first.