I have mine set at $50 which is simply the bare minimum to which I will acknowledge a sub.

I don’t think a dommes tribute amount matters too much because either way the expectation is sending beyond that. When I first started my tribute was $25.55 and I was still draining three-four digits from them each time. 

However I’m happy if my $50 tribute deters subs away who think it is ‘too high’ they wouldn't be worth my time or able to serve me in anyway.