Your returned format will be limited by the return type you declare. So yes, you can declare the property as a string and return the formatted value of something. In the "get" you can put whatever data retrieval code you need. So if you need to access some numeric value, simply put your return statement as:
private decimal _myDecimalValue = 15.78m;
public string MyFormattedValue
{
get { return _myDecimalValue.ToString("c"); }
private set; //makes this a 'read only' property.
}