A couple of questions from the new guy

Hi folks - I'm new to the forum and generally new to affiliate marketing too. I come from a (relatively) successful online retail background. I took some time off after I wrapped my last online store up to spend time with my new baby which was now about a year and a half ago so its time to get back to work and start earning again. I've got a few questions that I've been unable track down a definitive answer that I hope someone here can answer.

1) I've read a lot of different estimates as to what an email list is financially worth - the figures I seem to see most often are $2 - $4 per email / Month for a well targeted healthy list. Are these the type of numbers you successful guys are seeing? I know no one wants to disclose their earnings and I completely understand that, but (without disclosing the size of your list) is anyone willing to tell me what kind of figures you're seeing in the real work per email / month? - having an idea of list value will help me set goals

2) I started building my list in my chosen niche a week or so ago, I've playing around with different techniques to get opt ins using Facebook and Reddit ads. I seem to be getting opt ins for around 30 - 35 cents each with the few campaigns I've been playing with so far. Does this sound like a reasonable cost per opt in?

Thanks in advance for any insights from you experienced email marketers out there

Cheers
Chris