50g new for Us $550!!?

[severedgarden]

Hello,
Sorry for the 'nearly off-topic', but I have a question related to the 50g

I have one, used but in perfect working order, with its 'cloth' (not leather) original bag.

I want to purchase a HP Prime G2 so I am thinking of selling the 50g

Could you point me in the right direction about a fair selling price for it?
Thank you.

I am based in London.

Cheers!