Having the original cover disks/CDs would make a difference, too - in the case of CDs most people would find them more valuable than the magazines ...
With a CD I'd say a fair price would be £3 - £4 each (listing what the CDs contained), with a disk I'd say £2 - £3 ea, on their own £1 - £2.
Of course more if someone had a particular stiffy for those particular mags, but there's plenty of people out there who have piles of mags they'll never read again, so they don't accrue value for ALOT of years (I just chucked out about 100 car related ones that nobody round here wanted).