I look over each spool and make sure they are in like-new, unused condition. I have another category for used vintage spools.
Silk buttonhole twist is absolutely magic for handsewn buttonholes! I love it in all situations except when making buttonholes on lightweight fabric, but for medium and heavy weight fabrics, this is my go-to. The pearls on the buttonhole stitch are so delicious and the buttonhole just about makes itself with this magical fiber.
all the various brands of silk buttonhole twist (all vintage as well as all new) sew up the same in my experience. the price difference is due to volume as well as packaging (plastic spool, foam spool, or wooden spool). in general, coats and clark come on a plastic spool, but a handful come on a wooden spool. in this case, you aren't getting charged for a wooden spool (just a happy upgrade).