That's a huge subject man, I was all about researching oud's for a bit until I realized that the pure oud oils are stinky beasts !! hehe.
I am partly joking but man it's like more of an additive than something I could ever wear and all the samples 30 ish of them are in their own sealed container because just the smell coming from 1 vial would taint an entire collection of samples.
There's a large thread in here where people discuss ouds and mukhallats etc which are like mixes with oud but I am not sure if you really want like anything that smells like real pure oud.
Here's one of the threads that was huge that I read through to find a few sites to sample from.
Depending on what you are looking for I am sure some oud experts will chime in with some choices ! You might not even have to go synthetic there are all different ranges of perfume oils and mixes that have real oud that you might like that aren't expensive.
I would sample like crazy though because some of the mixes can go from a sweet dried candy fruit and musk all the way to a barnyard full of cow pats !
It's a very wide variety almost like asking what's the best Musk ! :)
Good luck on your hunt !