Since I have had her in rotation for two years, and I wear her about half the time, we could conservatively say I've worn her about 300 times in the two years since she's been made. (Allowances for cold spells and colds, when I break out the flannel). I believe I spent about $50 on her materials (certainly not more).
50/300 = .16667, or 17 cents/wear.
Well worth the money and the time. Well-worth it. When you think of your clothing as "$/wear" you can really break out of the fast-fashion rut of wearing things that are cheaply made and disintegrate just as quickly. Now, sure - if I'd made the same gown out of cotton flannel, we wouldn't be having this chat, because it'd still be going. And half the price too. But - hey. Silk. :)
For me, sleeping in silk is the best of all possible worlds. My husband likes me to sleep in soft things, I can't abide polyester "satin", and real silk warms to skin temp in seconds. It is intrinsically sensual.
Which is a good thing, because clothing designed to be slept in is *not* sexy. (You have to be able to move about quite a bit). My silk nightgown is not a bit of conjugal costuming. It's extremely comfortable as well as being lovely. No, it's no boned corset... but I'm not planning on sleeping in a corset!
Sewing details: I used about three and a half yards of silk charmeuse ($60). I used the peasant blouse pattern that I've been using for everything these days, lengthening the hem from hip to brushing the top of my foot. It's embroidered at neckline and hem, gathered at the neckline. French seams throughout. Perfect? err.. no. But it's good. And it feels *divine*.
On the personal level, I started and finished this nightgown today, having finished DH's shirt yesterday and prioritizing "replace nightgown" over "make a new skirt". Feels WONDERFUL - exactly what I needed today. :)