I don't consider bike commuting a wage I pay myself. The most direct cost savings would be the $3.40 each day I spend on the T on days I don't bike or the ~$120 per month for parking (but I am highly unlikely to ever commute by car in Boston). I bike commute partially because it keeps me fit, but mostly because it is fun!!
Someone somewhere costed out all the financial pluses and minuses of bike commuting. If it keeps you from owning a car or an additional car, there is a big savings. If not, bike commuting is very close to a wash.