Inks ?

This is cheap from www.999inks.co.uk. compatibles for my Canon Pixma iP4000 printer.
Anyone out there had some from them if so what's your thoughts?.

The add appears to say this lot for £10.45
4 Canon BCI-6K Black Replacement Cartridges
2 Canon BCI-6C Cyan Replacement Cartridges
2 Canon BCI-6M Magenta Replacement Cartridges
2 Canon BCI-6Y Yellow Replacement Cartridges
£10.45 yet another site I've bought orignals from start at £8-each.