Snow had orders he couldn't take salary back. No team wanting Vanek had cap space, MB had maneuvered to make sure he had the advantage of cap space at deadline.
Vanek was a pure rental for any team as the whole league knew he wanted to go to Minny.
Many pundits/analysts were saying that GMs were skeptical of Vanek because he tends to disappear when it maters and boy were they right....MB didn't even try to persuade him to stay after that playoff.
I doubt the interest was that significant which is why he went for a bargain as you pointed out