The manufacturer recommends replacement at 105K miles for both the 4 and 6 cylinder models. The cost is about $400 more or less depending on your mechanics hourly labor charges. Do not wait to do it if it is at that mileage as these are both interference engines which means if the belt breaks the pistons will crash into the valves and destroy the engine. Make sure you use a mechanic experienced in Hondas. If you do not have one, go to:
Enter your zip code and you will get a list of mechanics in your area that other consumers have used and highly recommend. Look for ones that specialize either in the make of your car or the type of repair you need. Call 2-3 of them and ask for a ballpark figure on the repair. I have personally used this site with great success to find good honest mechanics and can highly recommend it. Good luck!