I know this isn't your question, but, if you're sewing a kilt by hand, you _don't_ want cotton-wrapped polyester (also called Dual Duty). The outer cotton wrapping wears as you pll the thread through the cloth, and the shredded coating winds up getting hung up in little lumpy bits in the cloth, particularly if you're taking out basting thread. I've also been told (although I've never tried to substantiate this) that cotton and silk thread eventually deteriorate, which is not something you want in a hand-sewn kilt. So, I use only 100% polyester.

I use Guterman almost exclusively for any permanent stitching in the kilt. I just wait until it's on sale at JoAnn's, and it's not that expensive. I do keep my eye out for cheap spools of 100% polyester thread in the sale bins at Joann's. I use this stuff for basting, because you use a lot of basting thread in a kilt, and you just wind up pulling it all out eventually. So, you don't need top quality. Just look carefully at the label so that you aren't ambushed by Dual Duty or cotton-wrapped polyester.