It really can be that cheap.. It all depends on what the shop charges per hour for labor. If you have a shop do it I would go to the honda dealership, get an oem belt, and then take it to the shop and have them install it. I bet that would save you some money cause the shops double the price on about everything they install... and you would have oem quality.
I bet it'll cost 150-300ish depending where you go.
dealership probably costs the most