I always "spring trapped" beaver, unless somebody NEEDED them out quick. Primarily, because all the other seasons were over, and I had the time, and had free'd up traps. As far as primeness of the hides. They are better the later in the season it gets. How much difference in $$ it makes, I don't know.

Castor mound sets in close to there, with a big trap on a slide, or snares like TD said if you can't find a den or feeder creek to get a 330 under water.