Depends where you start from to do any sort of comparison. Fully costed from scratch would include all your gear, the bike, a van maybe etc, or simply incremental costs of a season so excluding the above and simply looking at fuel for bike and van, entry fees, test fees, repairs, tyres, servicing inc oil and brakes.
Where do you put depreciation of van and bike? These costs are also net out of your disposable income, what do you really have to earn to pay for it?
What about putting a price on the opportunity cost of spending time with your other half and the kids?
For everything else, there's mastercard
WeeJohnyB