I would pay 300€ monthly for gas there :oops: (where is the crying smiley here?) Nobel goes the world to ruin, Kati ;)
We don't have gas, so I can only judge for electricity. We don’t pay significantly more than with our old "eco" provider, only that they are truly sustainable because it’s a private hydropower plant that you support with it, and there are a few other factors (I can't list them now, but there are countless documents about it on sites like Utopia). With gas, it’s harder to really be sustainable since gas is naturally more fossil and bad :D And 100% biogas probably costs quite a bit more.