We are in the business, but how many accounts are the original ones. How many original approaches to gain and convert traffic work now. Maybe just the domain remains as a shell, but that is it. In between a lot of work.
It is impossible to say what is reasonable price. Most likely it is zero, because seller has an advantage of asymmetric information.
Without knowing which market is targetted and how the buyer owns the market, the average value makes no sense. For example value of Uk market for me is nearly zero. Maybe someone can still make reasonable money there, but not me. But I can work with US, where many people make zero, because they had to take down ads.
Estimating anything here is like playing with shitcoins if not worse
If you talk to God, you are praying; If God talks to you, you have schizophrenia.