I tried the pigments being sold by Spot-A materials, I was told their latest ones are not yet on their website but they sell them ready to use in a pre-loaded Syringe - they charge €10 (one colour) each one is enough to to do 1L of resin at 0.5%. They work very well. Probably worth seeing what you think.
info@spotamaterials.com. I got them to post me mine and bought six colours, so the cost of the shipping was sensible. Still have lots left after several litres of resin.