2002 Buick Rendezvous

Electrical problem
2002 Buick Rendezvous 6 cyl Wheel Drive Type unknown Automatic 70000 miles

all of a sudden the right blinker blinks faster than the left. Then I couldn, t start the car by the key only by the remote starter and now the interior lights keep coming on and I have to shut them off, about 20 minutes later there switch on again, I know this is going to be expensive to repair but can anyone give me an idea of how much. Thanks