Glad to help!
BTW, the reason I say "usually" about countering is because if the offer isn't even close to the ballpark, it's obvious the buyer isn't willing to pay what I'm looking for. In those cases, I decline. Sometimes I'll counter, to which the buyer will counter another lowball. At that point, it's a "decline."
For example, if I have a $100 item and get an offer for $20, that's not even close. Sometimes I'll counter anyway with $75-ish as the best I can do. If the buyer comes back with $25, clearly, she and I are on different planets and I don't counter again. I just decline.
I don't know how some buyers can offer $20 bucks on a $100 item as per your example. I would be embarrassed/ashamed to submit such an offer.