It's OEM Epson ink, which breaks down to about $160 a liter. Most Aftermarket DTG inks at best are $25 cheaper per liter, so it's not really worth going with anything else.
Tried and true, Accurate colors and works great. 2 year shelf life for CMYK and white. Not that it would ever sit that long, but still beats aftermarket ink in that aspect too.
If you still DTG, DTG the right way with OEM Epson inks.