Buy one that has precharged refrigerant in the condenser. New units use R410a which does not deplete ozone. You'll also never need to handle refrigerant, only open a valve which release it into the copper lineset.
You can buy a Mr Cool unit, you won't need to cut/flare/vacuum the lineset, just connect. I don't personally don't use them as their units generally cost a bit more, (30$ ~ 50%) and you're stuck with whatever lineset lengths they offer. However it's a great starter install and work just fine.
Cooper-Hunter units come precharged, so fairly easy to DIY.
I was looking at Mitsubishi units, which I believe also come pre-charged. I don't know if it's a local law or if the supplier just didn't want to deal with someone not in the trade.
You can buy a Mr Cool unit, you won't need to cut/flare/vacuum the lineset, just connect. I don't personally don't use them as their units generally cost a bit more, (30$ ~ 50%) and you're stuck with whatever lineset lengths they offer. However it's a great starter install and work just fine.
Cooper-Hunter units come precharged, so fairly easy to DIY.