At some point, the open source models you can run locally are going to start to get competitive. I suspect the cost problem came from upgrading to ChatGPT 4 over ChatGPT 3 - right there their costs more than 5x.
Did they? I'm surprised to hear that. Hard to tell for autocomplete of course. For conversational answers, inference speed is _far_ higher than I'm used to from GPT-4, and lower quality. As in, it matches GPT 3.5/ChatGPT.
Not yet, it is still using GPT 3.5. The access to GitHub Copilot X (GPT-4) is in closed beta [1].