Instead of hording control of your budget, allow every employee to have discretionary control (and thereby responsibility) for a slice of the pie. The one area that is the scourge or bane of creativity is that every time you have a crazy idea, you have to run it by the head of the operation for approval. Unless you have some individual discretion over the budget, you have all the responsibility and none of the authority. Responsibility and authority go hand-in-hand. With out one and the other, you effectively run amok in a couple of directions. Tying together responsibility and authority gives people the latitude and trust that they deserve (and will earn) as they accomplish the aims of the organization. Of course, there has to be accountability, but if you subscribe to the "fail fast, fail often mindset," you have to be able to tolerate some risk for the massive gains innovation can bring. And, I might add, that very time an employee hears the work "no," in opposition to a request for a budget allocation, you risk losing your best and brightest to the competition (or another organization) that doles out healthy scoops of both responsibility and authority (manifest in the size of one's discretionary budget).
Let go of your ego. Open up the budget for all to see. Allocate funds to every one, size varies based on tasks needed to be accomplished. See what happens. You may find people binding together in ways you never thought to aggregate pools of funds to create bigger reservoirs of funds to try bigger experiments.