Everything outside of power equipment -- like HVAC, refrigerator, laundry dryer, etc -- is a rounding error on most power bills.
10W running 24/7 means about 7.3 kWh/month. In my area the average kW/h costs about $0.13 CAD
So a good rule of thumb is that every 10W 24/7 is about $1CAD/mo.
So assuming 30W for a laptop and 6W for a pi4, that means a difference of $29/yr. Which isn't a lot but isn't a rounding error either.
Even if that were not the case, paying an extra $2.50 / mo to not do ghetto fabulous bs with rpi and vlans seems like money well spent to me.