Part # Lookup Help

Does anyone know a better way to figure out the part #'s other than calling the dealer and getting the run around because they don't want you going somewhere else to get the part? They wont even tell you the number half the time? I just find it insane at this point, there is no system that allows you to plug in your VIN and get your part # online somewhere. I have a Volvo and I've spent way to many hours of my life trying to figure out part #'s. I know you can register with Volvo and get a login to their system somehow, but I believe its pretty expensive for operating a single truck. Anyways, I guess my question is, has anyone figured out a better way to do this? Or does anyone have experience getting the Volvo login? Is there any other software or online service that will help? I wish there was a site that did this, everyone would use it I would think. I would pay if it were reasonable. Thanks in advance.