Does a Valid Sale Require Price Display?
The question, as received
Is it necessary to display the prices of goods in a shop?
The answer
A citizen of any jurisdiction will follow the trading standards of his jurisdiction in terms of business practice. A resident of the UK will follow the Trading Standards of UK in terms of pricing. For example, the Price Marking Order 2004 outlines in detail the requirements in terms of pricing. The legislation can be read on:
In short: follow your jurisdiction's trading standards, e.g. the UK Price Marking Order 2004.
Explanation
http://www.legislation.gov.uk/uksi/2004/102/pdfs/uksi_20040102_en.pdf
For more information, you may read:
https://www.gov.uk/government/publications/pricing-practices-a-guide-for-traders
Fiqh basis
The Islamic principles of trading are based on principles such as mutual consent, transparency, justice, equality etc. These underpinning principles are realised through the Trading Standards in relation to pricing which one must follow as per the dictates of ‘Urf(customary practice).
And Allah knows best.
Mufti Faraz Adam
Based on the Hanafi school and on the question as it was asked. Another mufti may reach a different conclusion. Read the disclaimer.