Yer gonna get a lot of input on this one, with many different answers...
The book says 'inspect' at 100K. Our Valks range from 7 - 13 years old, and many have gone past 100K in that time. These are 'interference' engines, meaning that if a belt breaks or jumps a tooth, yer gonna mess it up bad.
I don't know how much an official Honda Belt is, but I seem to remember it's somewhere north of $40... Our own Jeff K has put together a 'Generic Parts List' (find it here -
http://www.jkozloski.com/generic_parts.htm ) that gives a few examples of other brands of belts that can and do work (Gates # 275, Napa # 250275, Goodyear - #40275). For about $11 each, I used the Gates belt when I changed mine.
My reasoning is if my belts are 10 years old or more, I'm not gettin' a warm fuzzy as I head out on a 1000 mile weekend trip. If I can give my self some piece of mind, for less than $30 and an hour or so of my time, it's money well spent. Most Honda cars say to replace the belts anywhere between 95K and 105K, or every 10 years (and that job goes for $500, on average).
Take the time to work on yer lady... Time and money well spent

Black Dog