Toyota's parts site seems to be their official parts online portal, that suggests nearby dealerships to ship parts to you. I searched for 0W-20 and found some under part number 00279TOW2001, which is described as "0W20 BULK TXM WTY" and shows a list price of $4.09, and unit price of $2.95. I ordered up 13 quarts, two oil filters, and a trim clip for my 4Runner, with a message in the "special notes" saying "If this is not 13 quarts of Toyota 0W20, please contact me before shipping."

The first dealership I tried called me within minutes of placing the order, and said that this part number was basically the bulk stuff they used in the service bay, and wasn't actually sold by the quart. They referred me to the usual 002790WQTE01 part number at $5.26 per quart. The second dealership I tried put the stuff in a box and shipped it for $9.95, and they're so close FedEx home delivery worked out to next day shipping speed. So it works out to about $3.72 per quart shipped for my order (not spreading the cost to the filters and clip), which isn't bad for an oil that my local parts counter charges $7.30/qt for. The oil was the usual Toyota black bottle 2790WQTE01 that came in 2 6 packs and a separately wrapped 13th quart.

I suspect this is a glitch that they'll fix, but it worked for me.

1990 Infiniti Q45 - M1 0W-30
2004 Nissan Frontier - M1 0W-30
2017 Toyota 4Runner - Toyota 0W-20