Google plugged the low-quality ad gap back in 2005 with the introduction of Quality Scores.
This means that you are no longer simply competing with other advertisers, you are also competing with organic search results. The Quality Score is intended to prevent low quality, or low relevance, ads to show up in search results harming the Google Search experience.
It is possible that you have unseen competitors that are not targeting your specific location, yet still competing with your ads in geographic areas nearby. So you can never rely on what you see in search results from a single location. There are usually competitors that do not show in your personal search result page for several reasons including geo-location targeting, daily budget limits, and ad scheduling.
However, bear in mind that you are not simply competing with advertisers, you are also competing with organic search results. Google doesn’t want to show irrelevant, or barely relevant results above listings that are more relevant. The Quality score and minimum bids help to prevent low-quality ads from showing in search results.
You would be better off selecting highly relevant keywords and set you max CPC bid at whatever level you are willing to pay, rather than waste time looking for keywords with no ads. There is usually a good reason those keywords have no ads, and advertising on such terms is typically a poor marketing decision.
I suggest you shift your focus away from low-cost keywords and toward high-value keywords that can be targeted at profitable CPC rates. (Value – Cost = Profit)