Seems to me that elfa more than make up for the the product price difference with their shipping cost. they quote 18euro for up to 1kg and diy-beamer quote me about 4.5euro shipping for the same product.
another alternative for aussies (and possibly elsewhere as they have a large number of international websites) is farnell.
If these are the same ffcs, not 100% but they look the same and have the same descriptions (ie .5 pitch 40 connectors etc)
aussie site ffc search:http://au.farnell.com/jsp/search/browse.jsp?N=500001+1000394&Ntk=gensearch_001&Ntt=ffc&Ntx=
uk site ffc search:http://uk.farnell.com/jsp/search/browse.jsp;jsessionid=OHBC5ACIEEHMJQFIAFNZK0Q?N=0&Ntk=gensearch_001&Ntt=ffc&Ntx=&_requestid=267102
About $9-$12AU (about 6euros on the spanish website) for the .5 pitch ffc's. So, they are not the cheapest kids on the block, unless you buy bulk, and although they are very flat and flexible I cant really think of enough uses for ffcs to order 100 of the buggers. Also, they dont do paypal so you need a credit card to purchase, but they offer next business day delivery to all major cities in oz, same day if you are in sydney cbd. I would imagine similar delivery times for other parts of the world from their local stores as well.