Stuart Halloway explains in numbers how picking Rails over Java affects the bids he puts in for consulting jobs. Since the actual programming is only one part of the bid, Rails naturally only has a chance to affect that part. But still, the approach that Stuart takes in differentiating between the two is quite interesting.
For applications that Justin consider “within the sweet spot of Rails”, the bid will usually be 30-50% lower. For stuff outside that sweet spot, the bid will still be about 10% lower than the equivalent Java one.