Yes it is very common for an employer to try to settle in that range at this point. The EEOC is not a court, as you know now, and cannot force any particular resolution. They can only get the parties together to discuss the matter and that's all.
So, following the EEOC complaint stage, an employer will only offer a very low amount. There is no reasonable situation where an employer would settle for $300,000 or anywhere close to that, at this stage of the situation.
This is because you still are not anywhere near actually obtaining a judgment against them. They have a great deal of time (perhaps a year or more) before that could be a possibility, so they have time to wait. It doesn't hurt them to now make a small offer, particularly if you took it.
Your next step, upon receiving an EEOC "right to sue" letter, is it find a local attorney and file a Federal lawsuit for discrimination. After you file that suit, the employer and you will go through the discovery process (where each gets to ask questions, take depositions and respond to questions). After that is done, then will come Motions where the case can possibly be resolved without a trial. If your case survives a Motion for Summary Judgment, only then have I seen employers begin to really seriously start offering settlements. It is because, at that point, the case can go to trial and it is trial that frightens employers, because juries are unpredictable.
Of course, you have to keep that in mind too. A jury could think you are 100% right, but not give you anything close to $300,000. They could give you exactly that...or more. They could give you $0.
All that said, until you get through that stage (summary judgment), I would not expect any serious offers from the employer.