if i buy used key fob would it work on my clio 2001?

I have a Renault Clio 2001 mk 2, my immobolizer light keeps flashing after the key is in the ignition and I've been told that my key fob transponder is broken and needs to be replaced, where can I replace this or if I buy a second hand one will it still work with my car?

jim
May 2012