There is no point, really.
If you think about it, any player that they would want to get to help for the Champions League would have to come from mid-table teams in the various leagues, who most certainly try to get every penny they can in the winter market.
You'd be overpaying even more than usual during this time.
You would have to be really really lucky to find someone, and to get a player from a mid-table team, no matter which league you are shopping in, means that you are most likely looking for either the best or 2nd best player on that club.
A team like that, unless they are blown away by the deal, would never give that player up.