I can get an aluminum cradle from LKQ self serve for 60 bucks here in Savannah, I was looking at doing the aluminum cradle as well. I did some research and found out that the 2003 and earlier Impala and Monte aluminum cradles are better because of the way they are made. the 2003.5+ started using an inferior extrusion design more apt to cracking. Just a little FYI. Here's the link i found that explains it.

Learn me about aluminum engine cradles - The Chicago Garage