While the questions "who the heck are you?" and "have you considered getting over yourself" are always good ones to ask, I wouldn't put too much soul-searching in before putting in a grant request. If you have good reason and can make a good case, put the request in and leave it to the folks awarding the grant to decide whether it's worth funding and, if it is, how it stacks up against the other requests that are worth funding.

Many perfectly good requests will get rejected for lack of funds, and many perfectly ungood requests will get rejected for lack of goodness, but that's how this stuff goes. As long as you expect rejection and your ego can handle it, you're fine.