If your looking to lower your C5 only one inch all the way around then NO, it will not cost $45.
No parts at all are required to do it! Check out the sticky about step by step walk through to lower your car! It's very easy to do, and required nothing but a few hours of your time!
I SLAMMED my car as far down as it would go, without having coil-overs, and it was FREE!
Just finished, will let the suspension settle and take a pic when the car actually lowers. I'm at 29" rear to fender lip, 27" in front, will see what it takes me down to. Actually I guess I dropped more like 2" all around upon further reading.