It can be very difficult to put a solid number on these things, as stated.
Believe me, I feel where you are coming from.
The problem is, a lot of these outrageously overselling hosts, have no staff to consider in their price, as they are usually youngsters looking to "get rich quick." You see them come and go.
The key is, there really is no limit. There is no "too much." It comes down to what you as the customer, thinks is ridiculous, or too much.
As long as the host can get away with it, without running into too much hassle, believe me, they will continue to push the line out a little further, until one day it the line can be pushed no further.....then they'll cross that line, if they think they can. At which point, a new limit (line) is set.
As long as consumers remain uneducated about our industry, they leave themselves open to be taken advantage of, sad but true.