These 'Cinderella' Stamps ARE NOT valid Postage at this time, they are 'collectors stamps'. They can be also be affixed to letters, cards, packages, etc - but as additional endorsements only - not instead of your customary postage stamps.
Click on the image below of the first in the 'Landscapes and Queen' series (St. George Beach) to purchase a 'Collector' or 'Cinderella' Stamp Sheet. Each sheet contains 15 pregummed and preforated stamps. Each sheet is priced at 1 shilling, 4 pence (15 1 penney stamps plus 1 penney postage) or US $10.50. Prices were converted to US dollars based on the 18 May 2007 London Close price of silver.