Last week I came across a study on Second Life by Forrester. In my line of work, Gartner, Giarte and Forrester are usually taken very seriously. Usually they know it and adjust their pricings accordingly.
In this case the study was about 10 pages text (and 5 pages notes, titlepage and credits and more bla bla) for a mere $ 750 (US dollar that is, not Lindens). Fortunately my boss picked up the tab :)
If compared to the Gartner study Forrester sees much of the same risks involved in SL business, though they've done a bit more research on the background and the evolvement of virtual worlds. Since it's priced at about $ 80,- per page, I presume they'll have my hide if I get into too much detail of the paper.