SERBIAN POST ABROAD - CORFOU:
I will say true, that in this field I'm really weak! But, I wish to show one nice sample of Postal Card, with cancel, that are in use at the time, by Serbian Post abroad (It sound like Serbian Empire, but this is an sad part in Serbian history where many-many Serbian civilian and soldier die in fighting for freedom).
What I learn from some catalogue is not lot, many catalogue have little information about this sad period from Serbian history, and some catalogue mention just envelope with postage (French) stamp on, and some even didn't mention it at all.
This sample (shown front and back side) are used on 1918 year, delivered from Corfou (Greece) to Dijon (France), with nice clear cancel. What I know from catalogue is that Serbian Post abroad existed between 1916-1918, and used French postage, with two kind of cancel, one that was obligatory "Ministarska Postanska Stanica" (Ministry Post Station) and second "Postes Serbes" that are placed sometimes over stamps, sometimes near stamp on cover. Normally - for this rare material, and because this material are important in Serbian history, fake are frequent on the market, and this is reason why to be very careful when purchasing online, preferable is to buy it with certificate and from trusted dealer. I see on eBay, that material from this period are valued very high, starting bid for rare items, are from 100-200 BP (British Pound) - Post Card shown have less than that, because it is common, and without certificate, but again will have an really good starting bid of 35-45 US$ - risky to buy, but worth to take chance. Premium price will be on postally used cover with rare destination, with two cancel + one more for censor mark which are common in black color, rarely in red.
Common cover, with French postage, set of 14 value on yellow paper, that will be very hard to complete, can reach more than 300.00 Euro on free market, and on white paper will have an premium of 20-25% more. Violet cancel will take another 20% premium, and if You will find this cover with Greek postage it will be miracle! More of this will reach samples with more than one stamp on it, also porto postage, mixed postage - all this will have an nice premium on market. But again, be very careful - fake samples are on market!