Hi,
Here is map of average radon levels in Connecticut.
Connecticut | EPA Map of Radon Zones | Radon | Indoor Air Quality | Air | US EPA
But this just shows the average levels of all test taken. You can always expect to find some high levels no matter where you live. For $15.00 it's very cheap insurance to run a homeowner DIY test. A radon mitigation will vary in different regions but typically $1000 to $1500 is average.
If you have any questions let me know.
Val