If you're willing to run a VM for a single app you are probably the type of person who is willing to spend the time to set up a Haskell tool chain and libraries for free.
Although I am most definitely not that type of person, all I care about is playing with the language. Anything detrimental to that is just noise and not worth the time. So I consider the $25 quite a cheap price to not have to think about the extraneous actions required to get a Haskell environment up and running.