Unit price is the price per item, but that's a term usually used when referring to tangible products. For example, if I buy a package of 8 bottles of shampoo for 240 euros, than my unit price is 30 euros per bottle.
As explained in Wikipedia, in the realm of business, unit cost is a business term that describes how much each unit costs to make, including materials, assembly, and labor.
I think you might be better off using web advertising terminology. Cost per display and cost per click are more common units of pricing for banner ads. Because each display is usually very inexpensive, displays are often measured in thousands:
CPC - Cost per click (CPC) is one of the online payment models by which advertisers pays for each click through made on their advertisement. This is an ideal method of payment for advertisers who need to guarantee they only pay for those viewers of the banner that click on it and visit a page on their site.
CPM - Cost per thousand (CPM) is one of the online payment models by which advertisers pays for every 1000 impressions of their advertisement. Prices typically range from $10 to over $50 per thousand impressions. This is an ideal method of payment for advertisers who want to guarantee only the number of people who sees their banner. The "M" in CPM is from the Roman numeral for 1000. The Roman numeral M was derived from the Latin word "mille" meaning "thousand".
Source: Web Advertising Glossary. A similar glossary can be found here.
Some websites (like this one) mention that CPC is a more popular model than CPM, but that issue is outside the scope of an English forum.
One way to say this is to use the word skill, or the expression more skilled, much like you did in your question:
Jeff always beats me in golf. He is far more skilled than I am.
Playing checkers with my 9-year-old can be boring. She just doesn't have enough skill yet to play competitively yet.
The Oakdale high school team couldn't compete against the Olympic volleyball team; the skill level of their opponents would simply be way too high.
Macmillan defines the word skill as:
the ability to do something well, usually as a result of experience and training
You can also convey this sentiment with the expression can't compete:
I couldn't compete against against Brianna Stewart. She's about 6 inches taller than I am, and one of the best athletes in college sports.
My son tries to play chess with me, but he just can't compete.
We could play darts for money if you wanted to, but, I'm telling you, you won't be able to compete. I used to play in weekly tournaments for about ten years.
We finally had to close down our burger restaurant. We just couldn't compete against the McDonald's across the street.
When compete is negated in the sentence, it often implies a gross mismatch like the one you describe in your question.
Best Answer
They are equivalent enough in general usage that, in the context you have provided, it doesn't make a difference worth worrying about.
As justification for that:
You would ordinarily use price for an item or product that could be purchased. This isn't necessarily physical. The customer can buy airtime for instance, and therefore price works in your example.
On the other hand, fee usually indicates payment for a service. This could be a consultation with a doctor or payments to the tennis club for using the court each week. In your example your service is the placement and display of the banners, so fee works too.