I have Burris Fullfield II 3-9x 40mm scopes on both of my slug guns. They ran me $199 a piece when I bought them about 7 or 8 years ago.
Burris makes a 4x Timberline scope for $149, and I believe Burris scopes are still made in the US. I know all of the Burris scopes I bought were made in the US and they have a forever warranty.
http://swfa.com/Burris-4x20-Timberli...pe-P10998.aspx
Ultimately, it depends on what your budget is for this new scope. You should also think about checking out ebay to see if they have anything on there worthwhile.