McLaren MP4-12c is the cheapest McLaren you can buy right now but the price tag is pretty big to be considered as “cheap”.
The 3.8 V8 gasoline engine is pretty much the only engine McLaren has and it looks like that they wants to keep it that way. We heard rumours a couple of months back that the McLaren is working on a cheaper version of the 12c. A car which is smaller than the 12c, lighter than the 12c obviously, and a little less on power. They said that they wanted to build something in the range of 911 turbo.