I'm curious now about ivona. How/where would one purchase acquire it? googling it seems Amazon may have bought Ivona to use with their Alexa system, the IVONA wikipedia article redirects to an amazon echo page. I found this site also
https://www.deskshare.com/text-to-speech-voices.aspx which lists individual voice purchase options, but I couldn't tell how you would use any of them since they are all windows exe downloads. Is there a definitive site that offers Ivona for purchase or download for linux? Lots of sites that do demos of the voices (presumably running the software on their web servers I guess) but I couldn't find any "purchase here and install this for linux" anywhere.