Have you made the game already and want someone to run through your events code and see if you are leaving gaps or conflicting events?
Or are you asking for someone to write the events for you? with a defined set .. or is it undefined yet?
Either way, it would be difficult to give out a cost to an open ended question :)
May be if you can list out more details, we can help.
Note, we do a ton of event handling in our code.. and also help others with their games - toonheart.com/services
Can send me details on email ( krish at toonheart dot com ) ?