Madeira 200m rayon are £2.20 at Jaycotts, but if you can get the right colours in 1000m reels from Barnyarns you would save quite a lot - they're only £4.45 a reel.
Barnyarns do give a discount for every 3 reels you buy, but it looks like it's only about 7% at the moment - I'm sure it used to be more than that. It makes the 1000m reels come out at £4.14, and the 200m ones come out at £2.28.