I've never been able to hang on to cash. Its my big failing. Even a foreign player brings in merchandising, not as much as an English player but still significant. Training takes a long time but as you're clearly aware it does mean you get a player with the specific skills you want.
I'm sure you don't need me to tell you this, but just because you have money, doesn't mean you should be careless with it. Spend well and good luck.