Hmmm.. first of all, to the thread starter...  think you need to correct the thread topic's title due to the grammar mistake.

Do you think a football fan must own the club's ori jersey? 

A is for a singular object. A football fan. If plural, then no need 'a'.. just 'football fans'

My view on this..

It's up to you. You support a football club/team because of passion. Passion is subjective... you love your spouse in your way.. it is subjective.

If you still want to buy fake jerseys.. it's up to you. If you feel like being inferior or no different to others because of buying fake jerseys, it's up to you too... But do not say that you cannot afford to buy original jerseys. There is always a way when there is a will......... Original jerseys does not mean that you cannot afford at all........... there are ways to buy original jerseys that don't cost too much.

And to those who think that buying fake jerseys doesn't do any harm.. think again. You are supporting the market.. and you are supporting the parties involved in producing fake products.. The workers hired in illegal factories.. the poor work conditions.. the underage workers (children), working in poor conditions (treated like dogs, tied up to machines.. I saw this in an astro documentary show)...

Remember the advert that Jackie Chan did once.. about illegal selling of products from endangered animals such as bears... "When the buying stops, the killing too.." Same case here.