I personally buy my supplies from MB Fibreglass and I've never, ever had a problem with their stock. They even stock brushes and acetone to make your stuff last longer.
Another concern I have is forming a visor. I may be able to find on online, but I would largely be guessing what size I need. I so not have the equipment to vacuum form my own. Are eBay visors generally easy enough to cut and bend?
Personally I bought the HJC 05 gold visor and was lucky enough to find them for £12 each, but seem to be almost twice that cost now. Not sure on the difference but the 03 version looks the same and is available for £13 on ebay.
As for cutting, very easy with a dremel reinforced cutting disc (SC409) and a steady hand. You need to keep cleaning away the rubbish so you can see what you're doing and definitely measure twice (or even more) and cut once.