There have been many, many Star Trek books out there. Some have delved into the histories of our main characters, some continued the story where the show left off, and others fleshed out characters and species we'd only glimpsed for a second in the show. How Much for Just the Planet? does none of that, instead trying to be world's first text-based musical comedy.
You're probably wondering, "How can a book be a musical comedy?" It's a good question.
How Much for Just the Planet? is a follow-up, in a way, to the original series episode "Errand of Mercy," where the powerful Organians forced the Klingons and the Federation into a treaty. A planet in the neutral zone between the two powers has a) been colonised by a group of humans who mostly want to be left the fuck alone and b) has also been found to have a large quantity of dilithium. (If you have ever wondered why every Starfleet captain starts drooling at the mention of dilithium, How Much for Just the Planet? describes an educational short film about that very subject. It's details like these that make the book a classic.)
The colonists of Direidi would mostly like for both the Klingons and the Federation to leave them alone, but they also know that the dilithium deposits make that unlikely. So they enact "Plan C" to drive both groups away. This involves the time-honored tradition of acting as strangely and irrationally as possible in order to drive both groups screaming back into space (or at least soften them up a bit before negotiations).
In the process, Kirk ends up involved in Shakespearean nightmare involving star-crossed lovers, Uhura is chained to a Klingon while they live out a Raymond Chandler plot, and Sulu and McCoy are captured by an evil queen who wants to make them her slaves. And best of all, Scotty has a duel with a Klingon, fought the traditional Scottish way: a round of golf.
Also there's a pie fight. I practically expect the announcement from Blazing Saddles to show up in this book:
How Much for Just the Planet? is a singular experience as a tie-in novel. Actually, it's a singular experience as a book, period. I haven't experienced a book before or since that contains song parodies (the theme from Rawhide stands out the most), a film strip, and cameos. (Oh yeah, John M. Ford gave other authors walk-on parts in his book. Neil Gaiman is the magician.) The references to other people, songs, movies, books, etc. all come thick and fast, and the ones I know I'm not getting drive me crazy, much like the crew of the Enterprise is driven crazy by everything Ford throws at them.
There's also an inflatable Enterprise copy and a starship which, due to a spilt milkshake, suffers from a nervous condition. The poor crew of that ship has their own parallel adventures, and it's actually nice to see proof that literally everyone in Starfleet has at least one totally bonkers adventure.
How Much for Just the Planet? is weird and funny and perfectly balanced and paced. Farce is hard comedy to write because of the way it has to ramp up. Ford does it perfectly here, while also keeping true to the tone of The Original Series. McCoy explains why he, Sulu, and two Klingons aren't going to bow to the queen of their captors this way: "You see, ma'am, these two gentlemen already have a dictator, it's against Mr. Sulu's religion... and I'm a Democrat." And I can hear DeForest Kelley say that line.
Trek is so very rarely good at intentional comedy, and the best it ever got is How Much for Just the Planet?, a book that fills me with joy every time I read it. I own at least three, maybe even five, copies of How Much for Just the Planet? (Several copies are being loaned out.) Every time I see a copy in a bookstore, I buy it. I also own the ebook version. I'm a How Much for Just the Planet? hoarder, and my body will one day be found crushed under a pile of many versions of this single book. I have no regrets.