£10 for a DVD-R and you hand over that much without question?
I'd love to be your media supplier, I really would

I'd be one smiling Mother F'ker thats for sure hhehehe
Traxdata Disks for about £1.40 to £1.80 a pop .... Work in EVERYTHING that we have tried (that supports dvd-r obviously) and they record to full capacity without problems.
In UK try SVP communications (www.121cdr.co.uk) or BigPockets (www.bigpockets.co.uk) for some good prices on good quality (and not so good quality) DVD-R media.
My advice would be to avoid bulkpaq, datasafe and unbranded disks for everything except PC use as results are unpredictable at best (some have good results some have bad but I perfer to play safe).
Good Luck