Yes, you can adjust the max CPC bid of keywords in a campaign for a particular source by either increasing (up to 500%) or decreasing (min -99%) the Bid Adj. for that source – thus allowing you to bid differently for each source.
1. Login to your Advertiser Console.
2. Click Campaign >> Sources tab.
3. Click on Bid Adj. against the desired Source.
4. Key in the new bid amount in the Bid Adj. field.
5. Click Save.
You can modify the Bid Adj. for more than one Source at a time. For details on the same refer to ‘How can I bulk edit Sources for my Campaign?‘
NOTE: Depending on Bid Adj.(+ve or -ve) that you set, the final bid will be greater or lesser than the default bid set at either the Ad Group level or the Keyword level itself.