While I certainly would be upset to see the Sox overreact and give away a top level prospect for Beltran, I wouldn't be at all opposed to putting together a big package to get Hunter Pence. You don't trade away blue chip prospects for veteran players who's best years are behind them, but to get a guy in his prime like Pence, it's something to consider.
A package consisting of Iglesias, Reddick, Weiland/Doubront, and another mid-level guy would be where I'd start. It would dent our farm system for sure, but we'd still have Renaudo and Kalish waiting in the wings, and given Theo's excellence in stockpiling draft picks and finding really good players throughout the draft I'd be willing to do it to get a guy like Pence in the fold.
I can only imagine how awesome our offense would be with Pence in RF... he would be a monster in Fenway IMO