I think you might think I'm talking about them applying it across all airlines? I'm not, just that this airline isn't discriminating on different 'types' of weight
My back of envelope calculations, feel free to pick at them as I'm sure they're probably out by a decent margin and make a lot of assumptions:
Embraer 195
63,900lb empty
28,600lb max fuel
Max range 2,593km (so I'm assuming that's an empty plane with a full tank)
Jet fuel is $3.20/gallon and weighs 6.7lb/gallon so the plane holds 4,250 gallons
So it weights 92,500lbs full of fuel and goes 2,593km using 4,250 gallons, thats 0.046 gallon/lb of weight = $0.15/lb
So a 150lb 'weight' costs $22.50 to go the 2,593km
200lb would cost $30
If I'm even remotely close then that means additional weight over the plane+fuel isn't even such a big deal (?)