PU Bushes ? Help

I bet this question has been asked before so sorry in advance

But please can you help?

I currently have standard Triumph rubber bushes fitted in my wishbones. The wishbones are as per the book or at least Ron Champion gave them to me free of charge when he first started.
Because of Building a house and things I have not actually touched my Locost for three years. I have since started work on it again this month. I have noticed that the rubber bushes have started to sag. Are there any direct replacement PU bushes and where is the cheapest place to get them from

MNR are about the cheapest i've seen for book/triumph wishbones

http://www.mnrltd.co.uk/Suspension%20Components.html

Thank you for that