Looking on Amazon, branded memorex 100 CDRs are about £13, DVDRs are £19, incl delivery. I looked at Disk depot and theres some (unbranded) for £7 but with £6 delivery it works out the same. Are there any cheaper places than Amazon? I'm not too bothered about the brand.
Be aware that some cheapie brands may have limited uses. I have a Datawrite pack which is fine for most things except Windows Movie Maker cannot write to them but it works on cheap Woolies ones I grabbed on their last day of trading.