With good setup and planning, you could probably do it faster out of bar stock, but parts volume would need to be huge (Since you have a CNC mill, that would mean more work for you).
Have you considered having the parts machined from sheet plastic, or plywood? Most plywood is crap, but there is some stuff you can get a specialty wood stores know as baltic or russian birch plywood (Cabinetshops use it for drawers because its really really dense and sturdy. Also, might the parts be made from HDPE in sheet form>?
The grip, someone mentioned its not incredible comfy. You might try making it a bit smaller, then once its all assembled, slap oogoo around it, and grip the oogoo with a soapy hand (oogoo wont stick to your soapy hand), to make a kind of custom fitted grip.
I ask about the machined options because thats what i have. I have a Very large CNC mill/router.