Can you outsource innovation? Can you buy an innovation as an outcome from a consultant - much like you would but a business process, a compliance certification, or a piece of information technology?
Of course you can buy a contained and discrete innovative solution or product. But I am referring to innovation as a culture thing here, something that innate to the being of your organisation.
If you want to be innovation, it requires thinking, self discovery and self reflection. Your organisation as a whole have to do it. It has to live and breathe the attitudes that are required for innovation.
Getting an innovation consultant in to give you the three cool answers is not being innovative. Certainly not in a sustainable sense. As soon as the consultant leaves, you are right back where you started.