to write my bot, its taken about 2 years, we even threw him a 2nd b'day party. However, its continous development, so i work on him (its a him) whenever something needs adding or fixing.
I would estimate i've spent about 100 hours on it in total, but he runs from information pasted from a game, and the format the information is in keeps changing, so that accounts for a lot of the time spent.
He has over 4,000 lines of mIRC script btw