@Frank ly
Home brew.
It's the way forward.
At the strength I use (0.3%) 1L of nic base made me litres and litres of liquid. around 16-18 litres if memory serves. It's in the cupboard steeping away.
A few quid and a freezer drawer for Nic base and i'll be set for years. They can't regulate the PG, VG or flavour concentrates.