CAMRA chief executive Mike Benner has urged pub goers to support the consumer group's bid to overturn the Office of Fair Trading's (OFT) ruling on the beer tie.
CAMRA is now taking donations via a new website - www.camraappeal.org.uk - in a bid to fight the OFT's decision not to investigate the beer tie further.
CAMRA had initially made a 'super-complaint' about the tie, stating that the high beer prices tied licensees have to pay has a detrimental impact on consumers.
It now wants pub customers to help raise "tens of thousands of pounds" to fund the appeal at the Competition Appeals Tribunal.
Benner said: "We are today calling for pub goers to support CAMRA's campaign to secure a fair deal for consumers by donating to our campaign to ensure the beer tie works in a fair and competitive manner.
"CAMRA has found that a lack of competition in the UK pub market is costing consumers £2.5bn a year, as well as harming the pub-going experience through reduced quality and choice. The lack of effective competition is also a key reason why seven pubs a day are closing, causing irreparable damage to local communities.
"Regrettably the OFT did not examine competition in local pub markets which is why we have taken the decision to appeal. The OFT's assertion that consumers benefit from a good deal of competition and choice in the pub sector is in our view not supported by the available evidence.
"CAMRA has pledged funds to the appeal process and is urging consumers to contribute to ensure our campaign stands the best chance of success. This is an historic opportunity for pub-goers to stand up to unfair conditions in the UK pub market and to assist the Office of Fair Trading in understanding the scale of harm to consumers.".