How do you if replacing the blower motor resistor on a 2002 Impala is necessary and what is the price range on a resistor?

I had to replace a b.m resistor on my 05 Pont. Grand Prix and it was not that difficult and saved me a bunch of money. As fas as I can tell, and as in my case, if your blower motor is staying on high (even with the key out) then you have a bad resistor. The cost of mine for the 05 was $70. It was actually cheaper at the dealership and was in stock. It was really simple to replace. On the Grand Prix it was located under the glovebox. It's not very big and should have a wiring harness running into it and then from the resistor to the blower motor. There were two screws holding it in and just the one harness to re-attach. If you have anymore questions let me know.