I bought a bunch by mistake. I will, maybe, use it all one day! In the meantime I can let you have a gallon packet (US). That will last for ages! 2 baths are very long lasting.
Another alternative is to mix your own, should you be handy with brews. Try Barry Thornton's 2-bath. As far as I can tell it's pretty much the same stuff. Barry's Better Brew.
Curiously, it probably didn't make much difference making 4.5L as against 3.8L, in fact.
The way 2-baths work you just leave it 'till the time is up - a slightly dilute bath would probably give the same results.
Cheers.
Murray
Brisbane.