It's not unusual for younger dommes to use a bit of hyperbole when advertising themselves as the "best"... which is a highly relative term!
As for the lower rate, she might be desperate for cash and is lowering her rate to get more volume. If she's advertising on backpage, then you know she's seen the ads and knows the going rate.
I'd say if you are curious, check her out and let everyone else know how it turned out. Might be that she is a bargain at the momemnt. Or... you might just have to take one for the team.