Oceania too: Australia installed 442 MW of residential solar and 2.5 GWh of residential batteries in the month of April alone. Both numbers are partly juiced by changes to a rebate program from May, but the overall trend remains explosive growth.
Watt-hours and joules are the same thing, and you are indeed technically correct, but you'll get funny looks if you ask to buy an 18MJ BESS for your home...
Which is pretty much what Australian average price is. Average Australian domestic tariff is around AUD 0.30/kwh which is USD 0.21/kwh.
None of this touches on standing charges, I don't know how that works in the USA, in Australia for an average household it runs at AUD 1.00/day to AUD 1.50/day (USD 0.70/day to USD 1.00/day). For an average household the standing charge is going to add 15 to 20% to the tariff.
I'm assuming that standing charges are like meter fees here. I've paid as low as $0.25/day and as high as $1.25/day depending on where I lived. There's not much uniformity.