My rent here is cheap, but thats only because I'm a student staying at the on campus hostel, but some things in Japan are cheap regardless of who you are. Tokyo is flat, and even though it is quite large most of the interesting bits are close together, its perfect for biking.
I've been thinking about buying a second hand bike since I got here, but hadn't seen any second hand store. Well it turns out that its not much of a problem, because brand new bikes are ridiculously cheap anyway. I'm not sure what I'm going to buy yet, but this one is only 10 400 yen, which is about $115. Japan isn't really that expensive.