To Cambridge: Thanks
I was not aware that this had been published in paperback form.
$65 is a bit much to pay for a collection of letters. Some have philosophical content, some not. I actually borrowed a copy of this (hardcover) for my thesis preparation, way back in the dark days of undergrad. My favorite letter is probably the first - a glowing fan letter to Euler with a humble request that he read Kant's book Thoughts on the True Estimation of Living Forces. One can only imagine how that went over, because we have no reply. Other highlights - Kant may have enjoyed the affections of two women at once; Kant advises a woman to stop being such a whore.
If you can find this in a library, check it out.