Aerial for Fabia Estate - 2008

I know there have been a few threads about aerials, but was hoping for some help still. 

My 08 reg Fabia Estate Dance radio doesn't receive AM anymore. I've held the Info button and it said the reception is poor. I think it is the aerial that is damaged. 

Where have other people got their replacement aerials? It is the type that unscrews but then just folds down - doesn't come out completely. I phoned my local garage but they are quoting close to £40 just for the aerial! Looked on eBay but not sure if they are right what I see on there.