Blank disc shop have discs for 11.99 per hundred including vat only delivery to be added which is free this weekend I believe. A good quality disc will set you back around £14-£16 per hundred inclusive of VAT. Comet and all the others are more expensive as they only carry branded discs and they have larger overheads. One of the cheaper high street places used to be Office World in times where I ran out of discs. But again tehy still worked out nearly double what I was paying for them for these other suppliers.
I have purchased discs from these and Big Pockets for as long as I can remember sometimes buying 3000 at a time and I can find none cheaper.
Hell even E-Net distribution who supply big pockets can't beat them on their price at wholesale in those quantities.
Take a look and try them out - I'm sure you will not be dissapointed.