Hmm, good question. I've seen them on Etsy from $200 to $450 for queen and king. Average for twin is $175
You have to keep in mind how many squares you'll be cutting and clipping. I would do $200 for the queen/king since they are supplying the fabric (batting too?) and $175 for the twin.
I'm not really sure though, hopefully someone else can chime in who has sold them.