If I was in Gauthier's shoes, I would look at the big picture before making that decision. There are many factors to consider...
1-(this might be the biggest one) what are the offers for each. Obviously if you can get a lot more for one, that has to be factored in.
2-what is the estimated cost of signing each or both. If Price costs no more than a veteran back up(Biron) and the trade offers are not that good(lots of quantity but no quality), you sign both
3-what is the capacity to clear cap room to sign players meeting other needs(center, forward depth), if Hamrlik and Ak are unmoveable, you are more likely to trade Halak if he has a 3.5-4 mil cap hit.
4-Do you think Halak really is a top 5 NHL goalie or was he just a good goalie with a great year. Most believe Price is only coming up to his "peak years". This has to be considered if you are a smart GM, you can't just blindly go with Halak and trade Price because of the recent playoff run.