From English Word Information: -ia: (Greek > Latin: a suffix that forms nouns; state of, condition of, quality of; act of)
Examples of where it is used, that are relevant to your book title, might be these: Names of classes and orders in botany and zoology; such as, Mammalia, Reptilia, Amphibia, et al. Names of collective nouns; such as, academia, militaria, suburbia, etc.
Names of things relating to something; such as, pedodontia, orthodontia, psychedelia, telesthesia, et al.
Drawing on thousands of one-on-one interviews in more than thirty countries, Gerald Zaltman and Lindsay Zaltman describe how some of the world's most successful companies as well as small firms, not-for-profits, and social enterprises have successfully leveraged deep metaphors to solve a wide variety of marketing problems. Marketing Metaphoria should convince you that everything consumers think and do is influenced at unconscious levels--and it will give you access to those deeper levels of thinking.
As lingobingo suggests, it's a made-up word that sounds interesting, is eye-catching and has some basis for existence – it turns "metaphor" into "metaphoric," a collective noun for the metaphors being discussed in the book.
No, my fingers typed metaphoric and then changed it to metaphoria as you were typing.
On an added note, I only find metaphoric in the Urban Dictionary – the entry is from 2007, and has 5 thumbs up and 3 thumbs down:
when something is too exciting to be considered a "euphoria."
being a metaphor isn't necessary to be a metaphoria.
The art room is a metaphoria of kids eating lunch and trying to do homework.
And, related, is this passage from Metaphoria by Design Do you suffer from ecstasy over metaphor?
Posted Nov 15, 2017
Musing about how to combine symbolism and imagery to create power beyond words, brought me to “Metaphoria,” ecstasy about metaphor, which might be what I suffer from. Years ago, my line of thought brought me to two books with “Metaphoria” in their titles—one by a therapist and one by a Harvard Business School marketing professor, both of whom seem to suffer from a similar affection for metaphor.