So, I was browsing a site which sells old books and this was written by the seller for one of his books:
Sail the Seas of Value
What does that mean ?
I see a similar question here but the answer there hasn't been satisfactory.
To 'sail the seas' literally means travelling around the world on a sailing ship, but it's also used as a metaphor for participating in something and learning your way around it.
"He was only eighteen when he began to sail the seas of government."
"My grandmother is not ready to sail the seas of social media."
So "Sail the seas of value" (which uses the imperative mood) is a suggestion that you participate in 'value', or less poetically, cheap products.
Since the phrase appears along with the word 'fair' in the description of the book's condition, the seller is telling you that this book isn't in great condition, but is so cheap that it's still good value. It's up to you whether you agree.
The seller's name is Yankee Clipper Books. A clipper is a type of sailing ship, which may be why they've chosen to use this nautical metaphor.