I did a yoga style fold over waist, it's so easy (and comfy) it's become by favorite way to finish off the waist of pants and skirts. The flannel was from Wazoodle and the knit fabric on the waist was from the remnant bin at Fabricland. (I luuuurve the remnant bin, it's always worth a peek).
If you wanted to make your own pjs but a little more economical/green/ethical you could use thrifted flannel sheets and t's shirts for the waist band. I'm sure I'll make some this way too, I had these fabrics on hand so I figured I'd put them to use.
We've decided to go out for dinner tonight so I'm heading off to peel a whole lot of apples and pears to make into apple-pear sauce before we go.