There are a few sources. I got this Descam from Airsoft Club and modified it. The base cost was $250US for a knock off, but it got me a set of 2nd pattern desert for my collection:
Right now, this guy is selling more Descam (DPDU) Cordura of the sort I have already purchased from him:
http://cgi.ebay.com/CANVAS-CODURA-UNCOATED-CAMO-NEW-BY-THE-PIECE-415_W0QQitemZ8240278195QQcategoryZ28159QQssPageNam eZWDVWQQrdZ1QQcmdZViewItem
1 Yard is selling for about $13.00 US
This is my DPCU set that I custom modified as well:
I recently bought some nice Aussie subdued flags from Tim's Surplus for about $10 CDN a pop, but have not had time to put them on yet.
As far as custom sewing for the bulk material, its not that hard to learn, and you can make some things that are truely impossible to get. This is some of the gear I have knocked together on my own:
Good to see a growing body of other Auscam collectors. Good luck with yours.