For my last 3-4 trades with lower valued chips, I've been using (recycling) the cardboard coffee sleeve that comes with my Starbucks coffee (it's so you won't burn your hand on the cup). It fits 2 chips perfectly. I put the chip in a plastic flip and then put it in between the coffee sleeve and put a few pieces of scotch tape on it. Then I put it in a regular sized envelope with a stamp. If it feels a little heavy, I'll add a few more cent stamps to it. So far they all made it (knock on wood). I can't take credit for this though, I receive a baseball card in this manner and thought it was a great idea. Obviously with higher valued chips, I'd send it in a bubble mailer.

Great post, btw!