Greenville is a great area! I agree. There are some great homes here: http://www.drhorton.com/South-Carolina/Greenville.aspx

Little Rock, AR; Nashville, TN; Knoxville, TN; Birmingham, AL, or well north of Atlanta, GA. All are university towns, with a bit more diversity and inclusiveness than the surrounding areas. All are in low cost of living areas of the country, and buy low cost power from the TVA. Like most places, the closer in and more urban you are, the more expensive that cost of living will be. Just look at Buckhead or Franklin, and you will see lavish living that rivals anything Beverly Hills has to offer. And the further out you are, the more travel time and hassle there is to get to those urban amenities like the concerts, museums, and great resturants.

All meet your climactic and geographical requirements. However, that low cost of living will also limit income opportunities, and the surrounding less expensive rural areas can be close minded and unaccepting of outsiders, especially north of Atlanta. You have to pick your poison here. You can't have it all. Especially with your goal of off grid living. That is going to be up front expensive to achieve, no matter your location in the country.

Texas. We have no state income tax. Land can be as low as 2k an acre