Real oud is very powerful. It is one of the most expensive substances in perfuming, but I used the real stuff in my last woody perfume. A little goes a long way, so that makes it cheaper. Just a hint of real oud can be noticed in a blend. I actually limited how much oud I used because of the smell and not cost, because it was so strong.
Others here know more than me about synthetic oud notes. There are a lot of products to sort through.