NO i am not.
The details of the cost are the actual one. That's all you need to start.
BUT is it enough to succeed ? certainly not. But that's all you need to actually start. The more money you have for advertising the better.
If you have the budget, it is recommended to have a custom template so your site looks different.
I have a customer with default template (he just changed logo and 1 image) he has a thread on a forum with 25 pages already, he has more than 140 publishers and he is a very happy customer.
So is it possible to start your own network wit the budget I told you first ? Yes he is the proof.