I just returned from the Post Office with a part for a bike that I bought online (not through this site; through another). The seller shorted the postage amount and claimed "Media Mail". A Postal Inspector opened the package and found the part rather than media (it was obvious this wasn't media just from the outside of the box). I received a notice of short postage and had to pay about $10 to get the package at the post office. Just a reminder to beware sellers who charge for postage and then try to short it or claim "media mail", leaving you responsible for the difference.