There are some old threads about this topic but since things change (materials, vendors) maybe it's time to get an up-to-date overview of what's available and where.
Personally I'm looking at something available (for shipping) in the EU but for the interest of others if there are some good materials available anywhere else in the world don't be shy to recommend them here. :)
Sailrite has Odyssey, Top Gun, Sunbrella (plus a lot of others), all of which have been recommended for JR in the past. I don't know about their shipping T&C to Europe though so if anyone has hands-on experience that would be useful.
Weathermax has been mentioned (80 and 65 if my memory serves me correct) but can apparently be difficult to sew. Where have you bought these?
Jami Jokinen was using something else which might interest me since I will be shipping either to Finland or to Gran Canaria (where I'm currently located). Don't remember cloth it was though other than that his sail is yellow. :P
Personally I'm looking to buy around 60 sqm, for a 34-37 sqm sail (with margin for error and experimentation). With Odyssey as an example for $12.50/yard at Sailrite it looks like I'd need about 40 yards for ~$500. Will email them about shipping costs.
More alternatives?