I really don't think that this Gasol trade has suddenly made Mitch a great GM. You do have to give Mitch credit for some of their draft picks (Bynum, Sasha, Farmar, Mark Gasol, Crittendom, etc.) and he deserves some props for trading for Trevor Ariza -- but there is still the trade of All-Star type Caron Butler for Kwame Brown. That one is always going to hang over his head. Also, for overpaying Radman.
I don't think that Mitch gets any credit for signing Fisher. Fisher was pretty limited in where he wanted to go for the care of his daughter -- and LA had what he was looking for and gave him a chance to go back and play for the Lakers. This was huge for the Lakers because they really have benefitted from Fish's leadership on and off the court.
The Lakers didn't resign Horry because Horry wanted to go be closer to his family (for the same reasons that Fisher left Utah). Horry wanted to go to the Rockets but the Jazz made him an offer to play for a championship caliber team and with San Antonio's proximity, it made it a no brainer.
I do think, overall, that Buss has been very stingy with his money -- he has, at least in the past, refused to open his wallet to go over the salary cap. However, I don't think that the Lakers have always been smart with their signings -- they overpaid Radman, the gave Cook an extension although it wasn't that much, they traded for Kwame and got a fat contract in return. I do think that Buss is a smart business man and I do think that he WILL pay the luxury tax, if necessary (although he won't be happy about it), in order to bring the Lakers back to contention. Because, even if he has to spend more money in salaries and taxes, he knows that he will still make MORE money than he was making with the Lakers stuck in the middle of the pack. Some of this is because of Hollywood -- some of it is because of the Lakers tradition and history -- but for Buss it always comes back to $$$.