Best, Lowest Cost Method To Send A Coin

As we all know postage rates are crazy high . If you just have 1 or 2 coins that are common and not worth a lot of money ,then put them in 2x2 cardboard holders then use two pieces of thin cardboard ( I use cut up cereal boxes ),stick the pieces of cardboard in paper envelope and tape 2x2's in between the cardboards . Takes regular first class stamp .
For a lot more coins use padded envelope ,postage around $3.60 . Then of cause there's the Flat rate boxes starting at about $8.25 .

Everything starts with value, assuming weight is not a factor, and then how quickly you want it delivered. USPS First Class mail includes a tracking number and $100 insurance as part of the weight and package-dimension price. The higher the value and speedier the delivery time, the higher the price. Please be more specific about the kinds of coins you plan to ship.

Dealer I get foreign coins from used to just use a Safe-T-Mailer the size of a standard envelope. Put the coins in it, seal it, put plastic packing tape over all the edges, put a label and stamps on it and drop it in the mail. Didn't even put it in an envelope.