I tracked my expenses a few years back and I spent about $150, not including the annualized cost of purchasing that bike or a replacement. This year I bought two new bikes (one cheap, one used, so about $650 total), plus I estimate about $300 in upgrades and other expenses.
Another way I look at it is that I ride to work about 130 days per year, and the next cheapest means - busfare - would cost about $520, so I have that much to spend on my bikes each year before they cost me anything! Until this year I came in hundreds of dollars below that allowance every year.
All figures in Canadan dollars, so X 0.8 for USD.
Robert