I'm coming late to this party...
but I've had a couple of Buicks with the 3.3, it seemed like a very good unit. Aside from the usual alternator and water pump at 100-120k miles, the motor/trans was no problem. Never touched the injectors and related stuff. Unfortunately, if you can't DIY, any silly thing can get expensive!
The 3.3 has the injectors and everything where it is visible- or do you have the 3.1 motor? I understand that the 3.1 has everything under the inlet manifold where it is much more "fun" to get at...
Good Luck!

Jay