This Speed.com article
goes into to depth about the IndyCar engine lease situation and how the lesser teams who do not have an engine lease yet in place from Chevy, Honda or Lotus could end up not racing in 2012. The bottom line is that IndyCar did a deal with the manufacturers such that they lease every engine at a loss ($690K per year per car). Instead of setting the number higher but mandating that each manufacturer spend the extra money in marketing and promotion of a series in desperate need for more exposure, the manufacturers are spending what they would have spent on marketing to subsidize each car at a loss.
The end result is that each manufacturer has reached their minimum, although one can argue that Lotus should be required to do 5 more cars [They are currently at Chevy: 10, Honda 8 (10 when they add Coyne) and Lotus: 5]. Therefore, Conquest Racing, Ed Carpenter Racing, Sarah Fisher Racing, and any team wanted to add a 2nd or 3rd car that would push the manufacturer over their minimum required, are going to have to pay full price for their engine (whatever that might be, but believed to be in the $900K to $1M range).