Modern Warfare 2 via Xbox Live Games on Demand. The game was just added to the service and currently commands a price of $60. Please, if you must purchase Modern Warfare 2, buy it elsewhere -- like, literally anywhere else. You'll save some money.
Now, with that out of the way, two other games are now available on demand, namely Aliens vs. Predator and Rapala Tournament Fishing. The former will set you back $30 while the latter can be reeled in for $20. Finally, Sega has also announced that Bayonetta will strut her way onto XBL Games on Demand next week for an undetermined price. We're going to guess it's lower than $60.