My go-to source for affordable flannel... and on sale now. :)
Heritage Chamois Flannel - From $99
I grew up thinking LL Bean was the best in flannel and I think they still are. Maybe their styles haven't changed much, but if you want only a few choices, this is their best and warmest flannel. Thick and brushed, it's made in Portugal.
Organic Pinstripe Flannel Bedding - From $15.99
This is a lovely variation on the colorful flannel that is the usual fare. Much more grownup, this made in Germany from organic cotton flannel. (Sorry, it's so popular it seems to be a bit sold out right now... )