Price and quality are linked - if you buy the cheapest discs available then you most likely also get the worst quality available.
But there is some good media available at discount prices such as e.g.:
HP 8x DVD-R carton of 200 in 50pc cakeboxes for Â£25.99 at SVP
Same media code (CMC MAG. AE1) available as overprints at an even lower price, but I have no idea about the quality of these discs (apart from the single review posted at SVP):
Dshirt Overprint 8x DVD-R carton of 600 in 100pc cakeboxes for Â£61.89 for 600 at SVP
There is an aditional small discount available if you contact Steve at SVP and ask for a CDFraks discount (he’ll need your username here at CDFreaks). See this post.