Not necessarily so.....:-)
Like dazzling (work) I buy 48X Imation CD-Rs in packs of 10 (£5.99 per pack or three packs for £10) from Morrisons - they are of the highest quality and I've never had one fail yet. In fact I've bought enough to last at least two years.
The difference in buying 25, 50 or 100 in spindle form is that you don't get the cases; by the time you have bought 25, 50 or 100 cases to go with them, the cost is virtually the same as Morrisons's offer, which works out at 33.3p per disk and case.
Incidentally Dixons, PC World etc sell the Imation and similar packs at £7.99 per pack or more.