I have used a similar formula to justify all the bikes I have bought: I use public transit for commuting during the worst of winter (mid-December-early March) and rather than buy a monthly pass at $98.00, I buy tokens (10 for $20.00). If I am able to ride during those months, the tokens will last longer, but if I am not, then I have spent $100.00 for the month. About nine months of the year I can ride and, therefore save about $900.00 per year (approx., depending on weather). Taking into account that I would drop my insurance down to basic for 6 months of the year, that saved me another $700.00 per year and with no gas or maintenance during that period, another $600.00 savings was realized. I have since sold the car and no longer have any of the associated expenses. But, when I had the car I was saving about $2,200.00+ per year by riding the vast majority of the time. You know how many bikes you can buy with $2,200.00? I did that for 5 years. That's $11,000.00 I saved! Now, with only occassional cabs and infrequent car-rentals, it works out to what I used to spend on insurance alone. I have only spent about $3,000.00 on four bicycles during that period plus about $1,000 in accessories, so I am ahead of the game by $7,000.00 during that time.

I keep my gym membership because it is through work and only costs $10.00 a month and allows me to use all their facilities including shower, sauna and jacuzzi. It's worth it.