7075 or 7050 would be a good choice for this application. Both are high strength alloys.
Just your solid model files would be enough for a quote, export as IGES or STEP, most solid modeling and many CAM programs will read those.
Just a couple of thoughts on the part design, you might want to add some fillets at the sharp corners where the surfaces meet, will help keep it from cracking in the corners. And also put realistic radii where the endmill will be profiling the outside, at least 6mm or so.
Not sure about the finished cost, but there is around US$300 just in material and a lot of machining and setup time. That's a lot of material to remove.