Specialist fields include wartime memorabilia, and anything relating to aviation aces and other personalities, notably Douglas Bader, Amy Johnson, Sheila Scott. Space age souvenirs like newspapers are popular with some collectors, albeit some pieces are too recent to warrant high value.

Just look at these sumptuous recent eBay realisations:

* A Vintage United Airlines US Air Mail Wing Pin Badge went for $1536.11 with a similar item, not quite identical, following closely behind at $1250.63

* 32 Issues of Air Classic Aviation magazines from the 60s and 70s went for $455.99

Those things are not that difficult to find at local auctions and I venture it isn't the items themselves that fetched those high prices as much as the fact that just a handful of people worldwide were desperate to have them!

SPECIALIST CATEGORY: AIRLINE AND AIR TRAVEL POSTERS

Airline and Air Travel posters are constantly popular best sellers with some high realisations noted. Highest prices go to 1920s and 1930s posters with 1940s prices following closely behind. Artist drawn posters and early real photographic types are particularly popular, especially on minor routes to exotic locations. eBay's own recent top selling Airline Posters, both featuring zeppelins, include:

* Hapag Travel Poster with Zeppelin by Artist Anton (1930 ) sold for $2,600.

* By the same seller, another Hapag Travel Poster with Zeppelin by graphic studio Et Bauer (1930) went for £1526.00.

* Air Travel posters from French Airlines are enormously popular right now with several individual items fetching around the $500 mark in recent months for 1950s posters. Earlier specimens are almost certain to fetch higher prices. TIPS

* Condition is very important to final auction prices although really scarce posters should still sell well in less than perfect condition. Problem areas include water stains and foxing (can sometimes be removed or reduced); tears and creases, fading and writing or penciled markings (except autographs or important notes). Some faults can be corrected or improved by specialist restorers but you must always weigh up costs of restoration against likely improvement to resale price. On eBay, almost anything goes, and even damaged items fetch high prices especially for rare and unusual items. Find restorers listed in Yellow Pages or ask at local Art Colleges.

* Quality of artwork and artist's name can count heavily towards value so keep an eye on bidding trends and finishing prices for specific art and printing types (lithograph, chromo, watercolour, oils) and artists like Ottomar Anton (1895 - 1976) whose work is perennially popular. And pricey!

* Fakes are quite rare unlike reprints which have flooded the market recently for more popular posters. Some are marked as reprints, some are not, but pristine quality is usually a giveaway sign. If in doubt, ask for confirmation of printing date from auctioneers or sellers, look for older items sold alongside such as dated letters mentioning the poster. If you're still in doubt either don't buy or take great care in describing your items and offer a money-back guarantee against innocent misrepresentation.

CARE FOR YOUR POSTER (Applies to other types of poster, e.g. film, topographical)

* Never fold a poster for storage even one that has already been folder. Posters are best stored flat, away from sources of damage, like children, pets, stacked boxes, and so on. Otherwise open posters carefully, lay them flat, then roll them loosely and insert in one of those hard cardboard tubes used for posting delicate paperwork. They cost very little from major stationers and will keep your stock away from damaging light and can even help reduce some already existing creases.

* Do not expose items to direct or bright sunlight; this causes fading and can even crack delicate items.

* Wear gloves when handling really rare and expensive posters. The natural oils and dirt in your skin can damage or mark items.

* Light marks can sometimes be removed with dry bread or a soft rubber eraser but only on fairly common or more recent items. Leave cleaning and restoration of valuable items to the professionals.

* Keep all information about your poster buys for later reference, especially if you intend to sell your posters. Keep seller's details and descriptions, receipt for price and to prove your ownership of the item (note that stolen goods belong to their dispossessed owner and not an innocent buyer even with receipt).