I have to say that this is an absolutely, insanely detailed, fantastic article about query level bidding in Google Shopping.
It's scary to say that yes this is the traditional way that you would have to go about doing this. This kind of work can take weeks if not months to get through.
To be able to scale this for the SMB and the Big Brand our agency had to build an entire Software Platform dedicated just to creating and managing Google Shopping campaigns.
What is missing from this is the requirements of an ID level campaign and the tracking of transaction data from Analytics. With an ID level campaign tracking properly you can see which search terms sell exactly which products in a campaign.
However, unless you are also factoring in Cost of Goods Sold as well as Ad Spend and measuring that against the margin of the merchant, bidding can still wreak havoc on the campaign.
Click here to read the article