Application development

I’m looking at making an app to search through big audio archives for keywords. I’ve seen the APIs from Amazon and Google, and I’ve also seen Kaldi-ASR, which doesn’t seem to be available as an API.
It looks like I can choose between an easy way to build the app (AWS/Google) that’s fairly expensive per unit of audio, or spending longer making my own thing with Kaldi but it’ll be cheaper in the long run.
Am I missing anything? Are there any options that are both easy and cheap, or some other better compromise? Thanks