I bougth a second hand bike for 40eur 5 years ago, and I only had to fix the wheel once (5 eur). Never had to buy clothes, special locks or anything fancy... I use it daily...
I think for most cities, locks and lights are unavoidable costs, if you want to stay safe and still have your bike be where you left it... Some would argue a helmet should be too, but experienced cyclists know better than to open that debate up!
Unless you live somewhere with a great climate, foul weather clothing inevitably ends up needing bought if you intend to commute all year round by bike.
I think you underestimate how much a bike is more like an umbrella or coat to us than it is a transportation vehicle. But I do agree that in places where it's more like the latter, your comment applies. The nearest equivalent I can think of in Holland is the 'scooter' (moped?).
That said, you're now making me curious to what degree this applies to other cities, even just cities that are known to be bike-friendly. In how many cities is it normal (or even possible), like in Holland, to use bikes in this ways?
I've visited Amsterdam on several occasions, and I am always amazed at the low prices you guys pay for bike stuff, especially compared to the US/UK prices I am most familiar with. I found it similarly cheap in Copenhagen as well - I guess greater demand helps drive prices down.
The style of bikes that are popular in Amsterdam and other relatively flat European cities often aren't that commonly found in many other countries in my experience - the incredibly popular in Holland 'coaster' brake design (where you stop pedaling/pedal backwards to brake) is borderline dangerous on very steep hills, but works great in flat areas, making it pretty uniquely suited to cities like Amsterdam. Similarly, you guys rarely need to bother with gears, or need so few you can use much simpler to maintain hub gear systems rather than finicky external derailleurs. I've almost never seen a new bike sold in the UK with coaster brakes, largely due to safety on hills. Similarly, it's pretty rare to see a coaster brake equipped bike in the US. I sure wouldn't want to try stopping at the bottom of a long 30% grade in San Francisco on coasters...
No one uses helmets. Most people don't use panniers either; small loads are attached to the back of the bike by the default "snelbinders" (elastic straps). Or what's really popular lately are plastic crates above the front-wheel. Locks and lights (and reflective strips on the wheels) are standard on all bikes. In cities you'd get a second lock, but that's really about it.
As for the foul weather clothing; you would need a raincoat anyhow and a pair of rain pants won't set you back that much.
I spend about €15 a month on my bicycle if I spread out the cost of purchase, clothing, and maintenance (mostly parts, I do my own maintenance, which isn't uncommon here). That's for a high quality, extra tall bicycle (I'm 2m tall) that looks presentable enough for my daily commute to work.
A student could probably manage with €3 to €8 a month.
I live in the SF bay area now which has amazing climate and I still need rain shell and pants to bike all year. Better than the snow where I grew up but you still need gear to arrive comfortably and ready to work. When I went through all the costs, bike maintenance, lights, locks, pannier, rack, it was about $300 to get setup for comfortable bike commuting.
a lock is 10 euro and a front + rear light 3 euro in a dutch supermarket.
About the weather, it snows in winter and rains a lot during the year, you dont need special clothes, just whatever you would wear daily
Unless you live somewhere with a great climate, foul weather clothing inevitably ends up needing bought if you intend to commute all year round by bike.