To answer your question about where to buy IDC connectors, I use Mouser or Allied Electronics. Digikey will also have the, I'm sure. The biggest problem I have found with headers/connectors in general, is that finding the things via their search never seems to work. So I just bust out the big phonebook style catalogs to find what I'm looking for.
They can probably be found for cheaper, but if you just need a handful, I'd go Mouser.