I found out about Cepstral from being on the Asterisk mailing list. Cepstral offers fantastic speech synthesis, for dirt-cheap prices.

Cepstral offers Linux and Windows clients, and a handful of voices to choose from. Each channel costs only $30, whereas comparable speech synthesis software costs $600 per channel (or more).

They’ve got some online demos to try out, and you can buy and download the product directly from their website. If you’ve got some projects that could use a good voice, check ’em out!