I have decided to do a little testing, and I'm buying a set of cartridges from each of the following to fit into my Canon Pixma ip5000.
I will try to indicate quality / longevity and price.
http://www.tonezoneuk.com
http://www.disc-shop.co.uk/blank-media/ink-cartridges/
http://www.diskdepot.co.uk
http://www.premier-ink.co.uk/
These have all been recommended by PPRuNers over the last few years, but this doesn't imply that either I or PPRuNe endorse or recommend any of them.
If anyone wants to add any more recommendations please post a reply to this thread.
SD