If you have bought the Combustible and Snowblind maps beforehand, you spend around $20. The price of the new Dark Corners DLC is about $20 by itself; and the All Fronts Collection is also priced at $20. This means that if you bought every piece of content when it was released, you pretty much paid double-price, since fans who have held off can pick up everything for $20. To me, such has been the way things have worked with DLC; you want it right away, you pay more than the average shopper. A lot of fans were upset, however, and a number of complaints to Epic has caused them to readjust their pricing a little bit.
Recently announced, the Dark Corners DLC has been dropped in price from 1600 Microsoft Points ($20) to 1200 Microsoft Points ($15). While it is only a five dollar price drop, it is better than nothing, and shows that Epic is trying to make everyone happy. Dark Corners has been slated for release on July 28th, along with the All Fronts Pack as well, I am assuming.
Also, it has recently been announced that the retail version of the All Fronts collection has been canceled. In an Interview with IGN, Rod Fergusson had said that the retail version of the DLC has been scrapped "for the greater good". He also confirmed a juicy rumor about being able to earn experience while in Horde mode once Title Update 4 hits Gears 2.
Well there you have it; some interesting info that may entice me to put my Gears 2 disc back in the tray for a few more rounds of horde.