Target has 100% cotton sheets - they didn't look too thin and nasty to me. I've also seen them at Big W, but as we'd already bought a few sets from Target I didn't bother checking the quality.

I've seen a few different brands in baby shops - but they seem hideously expensive in comparison!

We're the same - neither DH nor I can cope with sheets that aren't 100% cotton (it feels like sleeping in a plastic bag!) so there's no way we're going to make our little one even try it!

BW