Maybe a soltion would be using static variables (maybe even in a static class),
or use "readonly" keyword. Compare this:
MyConstants mc = new MyConstants();
string strDefaultInstance = mc.strDEFAULT_INSTANCE;
string strDefault = MyConstants.strDEFAULT;
public class MyConstants
{
public const string strDEFAULT = "Default";
public readonly string strDEFAULT_INSTANCE = "Default";
}