In the EU €1800 gets you a 10kWh battery (ex install)

That's on the high side, I would guess. Depending on what brand you want, you can get 10kWh of LFP for under a grand right now in the US.

With a BMS and inverter? What brand should I be looking at?

	▲	rootusrootus an hour ago \| parent [-]
		You will get a battery and BMS for that price. Decent inverters are expensive, however, so you won't get a whole 10kWh setup with appropriately sized inverter for under US$2K. Probably twice that. I hesitate to offer any brand advice, because that is very situational, depends on what you're after, what experience level you have, what trade-offs you want to make, etc.