AMD Radeon Instinct MI50-32GB: best AI card for beginners ?

I recently stumbled upon this llama.cpp fork which supports AMD Radeon Instinct MI50-32GB cards ("gfx906"). That made me discover this card, and notice that some of them were amazingly cheap, around $250 used. The 16GB variant is even cheaper, around $100. I had long been watching AI-capable hardware for quite a long time, thinking about various devices (Mac Ultra, AMD's AI-Max-395+, DGX Spark…