If you get the Pilla (or whichever) inserts, might be worthwhile getting the frames alone and the lenses made by your local lens people (whoever makes your regular glasses), works out to the same cost. It's useful to have the option of moving the optical centers from dead center to where you look for your game. I ended up going in with my gun to the optometrist and having the tech figure out where the optical centers had to be based on my mount, final placement was a lot higher and over to the left, almost a quarter of the length of the lens away from the center.
They have the option for top-frame or bottom frame inserts (the one they show in the link).
My cost: 5-lens set with Panther Post was $600, plus $50 for the prescription frames, then the prescription lenses were $300 but this was covered by insurance. I've since added two more lens colours.
Interchangeables are nice when you shoot a lot of different backgrounds for tournaments and a lot of different light conditions, otherwise maybe a dedicated pair might do.
EDIT: I know a guy on the Canadian Olympic skeet team who says inserts and prescription lenses tend not to work for skeet since you have to look back at the house while holding your head at the pickup point, and there is a lot of distortion at the edges of vision (no matter the brand of glasses). Not sure if this is applicable to you but another aspect to consider if you skeet.
