Most people believe if they have paid for insurance, thier coin and currency are covered by postal insurance....think again!! I most recently changed addresses and have had numerous discussions with the local postmaster as well as many online chats with various members of the USPS Management Team in regards to insuring my coins and currency. It is commonly believed and posted online in many forums that if you can prove that a buyer paid more than face value for a note or coin, that it will be covered up to the amount insured, but not over the price paid. This is not true!! Please, before shipping a valuable note or coin, get it in writing that your coin or currency is covered. The postmaster has expalined that paper money and coins can be insured over face value providing it is 1) Shipped Registered/Certified mail with the proper insurance coverage and 2) In the case of loss or damage, you must be able to provide proof of value such as a copy of the auction or sale, or reference from hobby trade papers supporting your claim of value.
This puts many of us who sell common coins and notes along with higher priced rare coins and currency, as many times, it will cost more to insure and ship the package than the actual value of the package. Personally, I have always shipped any items of value over $50, certified requiring a signature. Anything of lesser value, I ship regular first class with insurance as it seems the post office is much more carefull with insured packages. I have never had an insured package lost with over  2500 transaction sent or received.
I whole heartedly disagree with these postal rules, but what can you do besides ship Fed-EX or UPS which is much more expensive and time consuming. I would urge anyone whodisagrees with what I have posted, to please contact your local postmaster, as I have been told many conflicting things from postal emplyees themselves. I've been told yes they will cover coin and currency only to be told the following day that they will not cover coin and currency. I finally spoke with the current Postmaster of the Lawrenceburg Indiana Branch today and was informed about the rules above.
I am hoping that I will save someone a lot of anger and grief that can be caused by this conflicting info generated by postal employees and online blogs. Of course, you should always contact your local post office with any specific questions. I hope I have helped.
Brian