I think it's extremely poor form on her part, and I definitely wouldn't buy from or swap with anyone who did this.
I went back through recent postings on the swap board, and found the products (and NCer) you're referring to. There is a HUGE disparity between what she paid and what she is now charging: a 43% markup, to be exact. A few bucks to cover shipping, OK, but this is inexcusable!
Just my two cents, FWIW.