It's a synthetic. To say every synthetic is plastic is like saying everything metal is steel.
But rather than argue the semantics of polymer chemistry

..
Steel pitchers that size aren't going to be cheap.
Here's one for $257.00
And
here's one that doesn't show the price, but looks to be about a car payment.
You can get smaller ones, about 1 liter, with tops in restaurant supply stores, usually used as coffee decanters. They are probably around $50.
They make a lot of steel pitchers without lids, as you've already found, but it wouldn't be too hard to make a giant stopper out of a sheet of cork or natural rubber.
I've also found a lot of stainless steel pitchers that size where the only thing plastic was the lid.
Bamboo is an option, but I've never seen one that size. It should be very easy to make one if you have bamboo.
If you want to be real country, you can probably find a large metal watering can with a lid.
