Breathes there a soul so vapid as to admit that he or she hasn't got the full set, but I've just been looking at Amazon UK. They have Vols 1, 2, 4, 7 and 8 on sale at £23.10p. That includes post and package if you're not in hurry and use their Super Saver service.

http://www.amazon.co.uk/s/ref=nb_ss_b/203-6541039-5222314?initialSearch=1&url=search-alias%3Dstripbooks&field-keywords=Greig-Duncan .

(Sorry about the non-clicky but I couldn't paste entire URL.