How to spend my $100 credit at Mobile Klinik?

So I got $100 to spend on accessories or a phone at Mobile Klinik. I don't know what to spend on to maximise value. They do have a refurbished S20 for $500 in "good" condition, which would make it $400 plus tax. Seems a little high for a refurb, what do you think?

Which accessories - which are not phone specific (like cases) - are a good value at this place?

Thanks.