Just a note that, while the listing on the Simon & Schuster website is for the US, the major ebook sellers in other countries usually offer the same or similar deals on TrekLit, updated monthly.
The best way to find out which deals are available in your country is to search ‘Star Trek’ and books/ebooks, then filter and sort by price.
In most countries, sorting lowest to highest will put all the ebook deals at the top. In some, like the UK, just set the filter to a low maxim price e.g., less than £2.99.