I ran Temple of Elemental Evil using MapTool and, I admit, I'm a bit OCD-ish so I used the PDF and copy/pasted the entire stat block and accompanying text into the token so that I'd have it available. I wrote a Perl script to clean up the pasted text because ... well, PDFs.
Then I had a macro that read the stat block from the token and assigned values to various properties.
That scheme took me days to develop and weeks to perfect, and it significantly cut down on the time required to prep an area, but I would've paid dearly for the ability to skip all of that! (It just wasn't an option at the time I was running that campaign.)
Having prebuilt encounters is definitely worth the money, IMO.