Financial problems, not really. Colony Capital bought PSG last year, and they don't want to give money for transfers. Last 3 seasons, they bought Yepes, Armand, Rothen, Kalou for something like 25-30M€ for all, and huge wages but results were crap. Except Kalou, who go to Lens for only 1,5M€ all this palyers are still in Paris, so it's expensive..
I guess they don't want to do same transfer politic now.. It's a reason why they bought good young players as Didier Digard from Le Havre in L2, so pretty cheap. And we can see good players from PSG Academy like Clément Chantome Yussuf Mulumbu, David N'Gog, Mouhamadou Sakho, who are playing in France NT in their age category or Younouss Sankharé, Loris Arnaud..
Concerning Pauleta, last year, Lyon have tried to buy him, they wanted to give him an amazing wage (same for Ribéry with l'OM), and Paris gave him a huge wage to keep him. But he only scored 15 goals, and he's a bit old at present so, he could leave France before August 31th..