When doing PPC on the search engines, you want your ad to be in one of the top three spots. This puts it above the search results, so it's first to be seen and get the clicks.
If the bids prices are getting too high, consider aiming for the sidebar or below the search results. The ad will get free impressions and exposure, while branding your domain name. And it will get some clicks, just not as many as being above the search results.
If you're doing retargeting using run of web, but getting no clicks, consider upping your bid price by 10 cent increments per thousand impressions. It's the same deal with RTB if you're buying remnant traffic on the top search results. Slowly up your bid by small amounts daily, until you start getting clicks on your impressions.
Keep in mind that PPC tests start at $200 and go up from there. You'll know within 300 clicks if an offer will be profitable. If you get 1% conversion, ad tweaks can triple it or more. If you don't at least 1% conversion after 300 clicks, pause the campaign.
Do not delete the campaign though, because the terms of the offer could change. Once the merchant sees no sales, they may drop their price, do a landing page redesign, allow bidding on their brandname and category, or some other change. In this case it's far easier to take the campaign off pause, than to do all the work setting it up again.
Many of life's failures are people who did not realize how close they were to success when they gave up.