If you want to bring data from multiple data sources into Google Analytics, there’s a tool that can do accomplish this really well:
They’ve got 3 different products, the one I’m referring to here is called Google Analytics upload.
This way, you can upload your cost data into Google Analytics, and then evaluate all your marketing campaigns’ performance from within GA.
(If you’re just advertising via AdWords, you obviously don’t need this. GA and AdWords work together really well and there’s no need for a 3rd party solution. But if you’re using other advertising platforms, this can help you to pull in cost data from all of these platforms.)
You can pull in data from any source, and even upload offline cost data into GA through Funnel.io.
They’ve got a quick explainer video on their product page that gives you the 2 minute overview of what you can do with Funnel Google Analytics upload.
Pricing starts at $149 / month