Fabrics n stuff ( my fave in the UK)
Ebay(search for ripstop nylon, you want the lightest stuff)
Diy gear supply, USA
Backwoods daydreamer, USA
Plenty more vendors in the US, may well work out cheaper than Germany or finland.
Pertex Microlight, Pertex 4( bit heavier), any calendared downproof lightweight fabric.
Down pillow-(hard to get the right quality though)
Have a look at them mate, decide on your colours/budget/intended weight and then you can check back in here to the great HF hivemind if your not sure.
Thanks for the info man !
Some of this I have heard before but some of it is going to be really helpful and I'll make sure to consolt the hivemind of HF before i go ahead with the actual making .