I liked my 5700XT. That seems to be $200 now. Ran arbitrary code on it just fine. Lots of machine learning seems to be obsessed with amount of memory though and increasing that is likely to increase the price. Also HN doesn't like ROCm much, so there's that.
What else in on the BOM? Volume? At that price you likely want to use whatever resources are on the SoC that runs the thing and work around that. Feel free to e-mail me.