Post Office has a rate called First Class, Large Envelope. As long as it is thin and fits through their checker panel slot, and weighs less than 3 ounces, it will go at that rate...usually $1.28 for two chips and lower for one.
Sandwich the chip between two index cards, staple in four places an use tape around the ends, it will fill the envelope nicely and go right through.
As I said in my header, I have sold over 100 chips in that envelope and using their rates for quite a while.
Hope this helps.