Due to his international celebrity, the singer Elvis Presley has been represented on stamps from all over the world, from Antigua to Tanzania. Post offices issue stamps featuring celebrities in part to reflect a diverse and ever-changing culture, but also for obvious commercial reasons. Many philatelists build their collections according to certain themes – for instance, transport or wild flowers. An Elvis Presley stamp would fit in well with a rock-and-roll themed collection or one devoted to the '50s.
Inspect the condition of your stamp, looking at both the face – the front of the stamp – and the reverse. To achieve its optimum value, your stamp needs to be in mint, uncirculated condition, with no franking marks. Ideally, it shouldn't even have been mounted in an album.
Make a note of the stamp's issuing country. With the exception of those from Great Britain, all stamps bear the name of the country that issued them. Some countries are more collectible than others. The recent Elvis Movies series issued by the British Post Office is worth approximately ten times as much as similarly elaborate issues from most other countries.
Take this information and go to the library in search of a multi-volume stamp guide. As of 2010, these guidebooks mostly come color illustrated, so you should have no problem spotting your stamp once you have turned to the correct country. The guidebook will usually offer both a used and unused value, the former being about one-third of the latter. Before putting the guidebook back on the shelf, make a note of the value and of the stamp's reference number (usually printed on the far left).
Go online and type the name of the issuing country, the denomination and the reference number into your computer's search engine. Hopefully this should bring up some specific hits from online auction sites and philately stores. Having that reference number from the guide means that you can be certain that you have found an identical stamp. Tracking several lots through to their final auction prices should give you a very clear idea of the value of your own Elvis stamp.
In 1993, the US Post Office issued a handsome commemorative stamp to coincide with what would have been Elvis Presley's 58th birthday. With a print run of half a billion, the stamp was a huge commercial success for the Post Office, but as of 2010, the stamps are far from scarce. Assess current demand by visiting online auction sites, and bear in mind that only pristine examples are likely to sell.
Elvis Presley stamps are often issued in groups within a brightly colored "sheetlet." If you have a sheetlet, don't break it up and try to sell the stamps individually.