If you?re planning on shooting CO with it, I?m not sure it?d be fully legal but I?m not 100% positive. CO rules specifically say the starting model needs to be on the production list. I?m not sure if it can be justified that it was an Accushadow to start, with an upgraded barrel etc.
It looks like a nice option though!
In my experience, you almost never get the cost of milling back (~250-300ish) and rarely the full optic value. But in all reality, the value is only what someone?s willing to pay for it. If it?s exactly what you would build, including the optic and all, and you save the machining time, it?s really up to you.