On Biblical Theology, Jim West asks "why books in JSNTSup are so bloody high". I assume that Jim is referring to the price here. As the editor of the series, the publishing and marketing issues like cost are a little outside my area of expertise, but I would like to make two points:
(1) The volumes in the series that are only available in hardback are still available at a 50 per cent discount to individual scholars, so you should never pay the full price if ordering for yourself. Just make sure that you order direct from the T and T Clark website and ask for your 50 per cent off.
(2) We are trying to bring out more of the popular titles in paperback too, and the book that Jim mentions, James Crossley's Date of Mark's Gospel is a case in point, coming out in paperback earlier this year.
Incidentally, the series title, Journal for the Study of the New Testament Supplement (JSNTS or JSNTSup) has now been phased out, and is replaced by Library of New Testament Studies.