I just burned through my third mini-split in 11 years in my freestanding office. 240 sf. The things are brittle and don't last. Original Goodman cost $2k for an original installation, pipes, etc. It's more expensive as a process to replace--because you have to cut and weld pipes, etc.
If you spend up and get a Mitsubishi or Carrier, AC companies charge $3500+ to replace. An AC company I trust (who just did the house HVAC) told me it's because they have to honor Carrier's 10-year warranty, and they know splits after about five years cost them dearly in service calls. So they price punitively.
One random AC tech recommended I look into U-shaped inverter window units for my office. I ended up buying a GE Profile U-shaped inverter, only 10k BTU, for my office. It's worked like a charm and has a SEER rating almost as high as a split. Cost $459, and I didn't have to pay for an installation.
If I bought a cheap Chinese split off Amazon, it would be $700 or so and then I'd have to find some installer to replace everything for $800 or more in cash.