Thanks everyone, I think these are all useful answers and helpful. I just wanted ideas of what's going on now.

Yes I have run into a variety of answers from the USPS. Counter one place and it's $1.98, (example) go to another and they want $3.98. I did get one of the guides finally. Like most things at the home office (back bedroom) it's "somewhere". But it did have the 1/4" slot in it.

I think for all the right answers and I'm saying all of them are correct and useful, the USPS doesn't know the absolute always correct answer to their own system.

Interesting, the 70c non-machinable surcharge stamp. That's a new one.

I think I'm going to go with what I used to do, which is a version of the notes card sandwich. Now I need to measure and weigh so I can charge a fair shipping price.

For a chip with some value, it's not as important, but for cheap chips, the postage starts to become a problem. Too high and no bids, too low and I'm taking money out of the transaction.

Thanks for all the help and advice.