My mini split blew a connection. When I used the argon from my welder, I had to buy a regulator off amazon. Pretty cheap. I had to get a fitting for the connection to the mini split. It was also pretty cheap. I also had to buy r32 from an online supply house. But it wasn't very cheap, maybe $250...
My opinion, make it easier and cheaper to do a couple of plain 24k btu models. Split them along the long side of the shop. If you're handy, it's very easy to do.
I bought 2 units last year. Only a few were 410a units. The vast majority were r32. That's what I got. No extra refrigerant was needed, but r32 is not a problem to find. I would pick r32 again if needed.