-I've seen Arlington in-homes in the $200-300/week range
-They tend to be, especially if they have multiple openings, but your chances are better if you find another family that has complimentary needs to yours - you need Tuesday & Thursday, they need MWF - and you approach the provider as a package deal.
-I think it might be hard to find a family provider who knows what their openings will be in spring next year (assuming you'll take a few months of maternity leave?), so I know it's nerve racking but just continue to read up on the licensing requirements and make sure you like them, maybe look for that complimentary family - which will be hard to find, and wait it out.