For single change gears and smaller items, I'd use a sample envelope.
This is a manila coin envelope about large enough for a dollar bill
_sewed_ to a small muslin bag with tie string. The invoice goes in the
envelope. You can mail one of these USPS insured for a pittance, less
than Priority Mail, by weight.

When you said one price, did you mean a substantial weight limit? I
think a Priority Mail 2 pound pack is overkill. I mean, what kind of
change gear tops a few ounces, or ever comes close to two pounds? Yes,
you pay the same postage....


You could prestamp them all with adequate postage for more than enough
weight, then just grab one, slip in an invoice, and drop it in a
mailbox. There's a limitation of 16 ounces on parcels into mailboxes
now. This would be below the limit.

Yours,

Doug Goncz
Replikon Research
Seven Corners, VA 22044-0394