When using the Spotlight search at the top right of a finder window, I often want the search to be non-recursive, i.e. only look at files in that specific directory, not any directories within it. Is this possible?
As far as I know, unfortunately it's not possible to do this.
Strangely, I also set the 'Document Container' criteria within Spotlight and it wouldn't show any results at all.
This is extremely poor behaviour, I agree. You can give Apple feedback on OS X (from which you can post feedback on Spotlight) here.
The command-line interface to Spotlight, mdfind, has no such capability. (There is an
-onlyin flag but empirically it's recursive.)
Since it's extremely unlikely that the Finder would have more capability than the command-line interface, I think it's safe to say that this is not possible. Sorry. That does sound like it would be a very useful feature.