You definitely get what you pay for with flies. I can put up with cheap flies which fall apart after a few fish but I can't put up with losing a decent fish because a poor quality hook straightens or snaps.

Fliesonline are cheap but the materials are not the best.

Fastmailtackle are also quite cheap but are better quality in my opinion.

Flybuyer (Fulling Mill) are not pariculary cheap but they are great quality and if you buy the 'tri-pac' flies they work out at about 75p each, which is pretty good in my opinion.