Yes, they certainly are collectible. In some cases, a canceled stamp is worth more than a mint one. Most instances this would be for a stamp on an envelope where the entire cancellation can be clearly read. Some collectors prefer used stamps as they are less expensive and less likely to get damaged.
Postal use of some issues are very rare. Tonga, which issued many 'variety' stamps with strange shapes, are very desirable on actual letters and not on philatelic prepared items.
As an example:
Many German stamps that were issued during the 1923 (inflation era) are worth more cancelled (used) than new. Example: Ger. 242A $13 new, but $3,500 used.
Not at the post office. Collectible stamps sold by stamp dealers would be subject to sales tax like any other retail sales.
Stamps are not allowed to be re-used. Stamps are marked with an ink stamp once they have been processed through the post office.
If you mean stamps for items of post you are sending to other countries, yes, Australia Post has a range of Australian International postage stamps, which are marked accordingly, in blue on the edge. If you mean stamps from other countries, no, Australia Post is not a commercial outlet for the post offices of other countries. Some of the larger Post Offices may stock packets of used (or CTO) postage stamps from other countries at minimal cost. The packets are usually focussed on a specific theme such as dogs, trains, birds, etc.
Yes, they are collectible. The US Postal service has jobbed out the printing of stamps and one of the requirements is that the glue on self-stick stamps be water soluble. That allows collectors to soak the stamps off envelopes so they can be put in albums.
Collectible stamps are stamps that people save that are filled away albums to show their other stamp-collecting friends later on. These stamps are issued by the post-office for a short amount of time with images on them that aren't of the normal. Some stamps show pictures of old movie stars or animals or pink ribbons. Stamp-collectors can also collect stamps from other countries. Some tell stories using postage material (Thematics or Topical collecting) others are more traditional and attempt to collect countries or areas of the world that they like, such as US or British Middle East or Scandinavia.
Mauritius 'Post Office' stamps was created in 1847.
Humidity will ruin MNH (Mint Never Hinged) stamps. Stamps should be stored in a moisture free environment.
No, you can not resell your stamps back to the post office.
All stamps are collectable. Whether they have value will depend on many factors including age, condition and rarity.
There are a few websites where an individual can purchase old stamps from Australia. Examples would include Atoncer, Ebay, and Collectible Stamps Collection.
Often pawn shops are the ones that will buy collectible stamps. In that area code there is a Shaker Coin & Gold that indicates they buy stamps. There are a number of others in the area. Look for Stamp Dealers in your zip code in the yellow pages or online.
they are marked like that because Iceland IS an Island