Can someone explain what exactly is chess informant is and why its cost so much ?

"... The latest edition, volume 115, is packed with topical material relevant for Grandmasters and ambitious amateurs alike. The present volume of 339 pages has much to offer. The sections on combinations and endings and crosstables from major events are there as usual. So is the featured great player – this time Nikita Vitiugov – who has his best games, theoretical novelties, combinations and endings highlighted. The longtime practice of featuring the Best Game and Best Combination from the previous Informant, judged by a panel of experts, has been continued. The heart of the Informant series, games annotated by top players with a special language less system of symbols, is still very much present and relevant. All this makes Chess Informant useful but the recent additions will only make it more so. First up is Garry’s Choice, where the great Kasparov dissects the top games of modern chess. His choice for Informant 115 is likely a game that has escaped most chess players’ attention up to know. ... Kasparov’s article is in English (not Informant style annotations) as are series of annotated games and theoretical articles by 2600 and 2700 Grandmasters that runs over 100 pages. This is really first rate material that is not to be missed. One can single out Romanian GM Mihai Marin’s 11-page contribution as one of the highlights of this volume. Rounding out Chess Informant 115 is a first-rate tribute to Svetozar Gligoric by Josip Asik. ..." - IM John Donaldson (~2012)

http://www.jeremysilman.com/shop/pc/Chess-Informant-115-79p3726.htm

"... Chess Informant is a tool that ambitious players can use to collect tons of material for training purposes and keep themselves abreast with the latest developments in theory." - NM Carsten Hansen (2011)

https://web.archive.org/web/20140627050255/http://www.chesscafe.com/text/hansen150.pdf

"... Many Books Are Outdated Quickly ..." - IM Greg Shahade (2012)

http://www.uschess.org/content/view/11614/675