Excellent though alarming article on journal price trends analysing price changes in the journals on the Brandon-Hill list and finding "that prices have jumped 51.90% from 1996 to 1999 and 32% from 1999 to 2002".
Update on inflation of journal prices: Brandon/Hill list journals and the scientific, technical, and medical publishing market
Joan B. Schlimgen and Michael R. Kronenfeld
J Med Libr Assoc. 2004 July; 92(3): 307-314.

