Of course expediency doesn't come cheap and a prior stamp will set you back one euro starting 1 January. At present you can get Bpost to deliver your letters for 87 cents a go, if they are in the regular format. If you are happy that your letter arrives within three days in Belgium you can still buy a non-priority stamp, but from the New Year that will set you back 95 cents!
People with a calculator handy will already have worked out that the minimum increase is a whopping 9.2% on the present price. The new higher rate stamps go on sale on 1 January. Buy ten and you will receive a 3 cent reduction Bpost informs us.