How much do you bid on revcontent?
Do the bidding prices increases depending on the traffic source? (Taboola, Rev content, etc.)
Bids depend on a lot of factors, the main ones are GEO, Device, Interests, wifi vs 3G ... It's not possible to tell you how much to bid on a source just like that. It can be anywhere from the minimum allowed bid all the way up to a dollar or more per click.
You will also see different bids from one source to the next, especially on placements that are exclusive to one of the platforms.
When working with revcontent for example, try to start low at first, around the minimum bid and see if you can get any traffic at all - in some GEOs it will work. Keep in mind that lower bid usually also brings lower quality traffic, so you will need to increase the bid after that initial test, but don't rush it, take it in small steps (10% for example).
Play around till you get position 1-5 for desktop and position 1-3 for mobile / tablet.
The higher your CTR the less you need to bid.
It often makes sense to run several campaigns with different lists and different bids since the market rate for widgets on revcontent have a huge spread.
There are several bidding strategies, and the approach that @Matuloo mentioned is good. But also you can consider going with average, or high payout, to analyze the traffic-cost correlation you get and adjust the bid accordingly. Otherwise you don't know how long will it take you to start getting quality traffic, and you are at risk of spending too much.