AC to DC low power Converter
Use a phone charger. more than about 10mA is too much for a practical transformerless supply

To get 150mA from 250V you need a 600uF X capacitor that's going to cost over $100 at digikey. (you have to put several smaller capacitors in parallel)

For a tenth of that price you can buy a 1W AC-DC converter module (and probably cheaper if you shop elsewhere.)