Good advice so far. Although I'm not sure about the self-addressed stamped prototype that X mentioned. I don't think that is acceptable evidence or an official method of protection.
I would suggest you might want to think about WHAT is going to be "patented". If you invented a pair of "clock sunglasses" (interesting idea...I'll have to google it) you'd want to get a utility patent. Getting a design patent means other people can make "clock sunglasses" but they can't visually look like yours. If someone hung a pocket watch from the glasses frame they could get a design patent. If you built a digital image into the lens that would appear by pushing a button on the frame, then you could probably get a utility patent.
Utility patents are worth much more than design patents because they cover "functionality" and allow for variations and different styles. You can make many versions of "clocksunglasses" to appeal to a wider market with a utility patent.
And just be aware, a patent attorney is not a teacher. You have to understand your idea completely before you get involved with them. That means how it works not just how it looks along with knowing your market.
Are you thinking of actually paying for manufacturing as in hiring people, insurance, rent/lease, payroll, health/pension plans or are you able to deal with contract manufacturers? And not to mention the easiest way to make a million dollars is to start with five million...
...ok so this is as close as I got in two tries:
http://www.google.com/patents?id=aDUrAA ... sunglasses
They'll never sell because they will only work with a round lens and the frames look crazy. This patent is worthless.