I have found a cheap source of sedge peat, but I find it difficult to
believe that this would be nutrient free like the bog peat, though I
haven't
checked online yet

Don't use sedge peat, I've learnt the hard way that carnivorous plants hate
it. I use Irish moss peat now, and they thrive in it.

I use a 50/50 peat/sand or perlite mix, and its works great for all my
carnivourous plants.

Regards,

Stuart Forbes
Edinburgh, Scotland