I have to agree with TVJon about market conditions in the area. They aren't great but certainly not the worst of the worst. I think North Liberty is very over-built...Coralville too. I don't like new developments, though, so I can't speak for you. I don't live in the area anymore but many friends and family members do (including a few friends that live in Swisher). I can't tell you whether or not to pay more than you want to and just buy the current house in question because obviously that's a personal call. Swisher/Shueyville is a fairly desirable place in the corridor and the people I know that live there enjoy it....but you can obviously only do what you're comfortable with...especially if you might be carrying 2 mortgages to start with.
Also, I'm wondering if you checked out the Ely area at all??? If not, you might want to go to
www.rmaxhomes.com and select Ely and check out some properties there. It's still in the College Community school district.
Regardless of what you decide to do, I hope you and your family are very happy wherever you end up living. Good luck!