Hiring developers doesn't have to be a loss, if you just hire 1 guy and let's say he charges $5-$10 each addon & you have a good STARTUP economy for the server that you know that you will surpass by getting donations. It's a risky move however.
However, if you expect donations and don't get them, you'll be in a bind. I just doubt, unless the addon is stupid simple, that any developer would only charge $5-$10 each.