Standby electricity consumption usually accounts as 2%-3% of installed capacity of equipment. Considering the installed capacity as 275 W (not all equipment is in standby), and 19 h/day average standby time (24 hours total-5 hours working) the total reduction of consumption will be 275 W * 19 h * 0.025 = 130 W.
The annual saving is 48 kWh for an average typical consumer.
This is 4-8% from the total consumption of 1200 kWh.
No investments, just creating saving habit.