Ridiculously cheap if you factor in the costs of time/effort spent learning to do it yourself when your primary focus is launching your jewelry making business.
Jewelry making businesses go to where the buyers are, which is Etsy. They could do Squarespace Ecommerce and work on SEO and PPC ads to drive traffic, but as you said, they might prefer to focus on making jewelry.
For me, it's not clear how Squarespace will be able to grow if their market is mom-and-pop shops. There are better economies of scale in targeting 1 enterprise accounts over 10 consumer accounts.
