Callybags is right. Nama only owns the loans, not the assets. But 75% of the loans are non performing - so it will end up owning or controlling the properties at some stage.
If whatever you have your eye on is a scheme/property owned by a smaller property developer, then Nama won't have it yet. Only the top 10 developers have gone over so far, the next 10 are close to being done.
You'll probably have to wait a while - perhaps until next year.