First, it is odd to me that these are priced completely identically. Given that these are entirely different backends, I'd expect some price variation. Second, these prices have not changed since at least 2018 in the case of Google [2] and 2019 in the case of Amazon [3]. I'd imagine that costs would have significantly decreased over this time, considering how much faster and abundant TPUs have become at both of these companies.
Does anyone have insight here? Are these services artificially expensive? For context, I'm currently running a FOSS service [4] for myself and my friends that scrapes articles, converts them to speech via GCP WaveNet TTS, and plays them via any podcast app. The average article costs me about $0.10, which is a pretty noticeable sum, even with my limited user base.
[0] https://cloud.google.com/text-to-speech/pricing
[1] https://aws.amazon.com/polly/pricing/
[2] https://web.archive.org/web/20180617113243/https://cloud.google.com/text-to-speech/pricing
[3] https://web.archive.org/web/20190819070148/https://aws.amazon.com/polly/pricing/
[4] https://github.com/rozbb/readtomyshoe