The
Madren Center in Clemson is really pretty. It's only about a 30 minute drive from Greenville and there is a hotel at the Madren Center. It overlooks the lake. It is popular though. I have two friends getting married there this year. I don't think it's too expensive.
There's also the little known
Outdoor Lab (http://www.clemson.edu/outdoorlab/conffacilities.html - broken link) at Clemson too. It's beautiful and perfect for an outdoor, almost rustic wedding. It's also very inexpensive ($600 to rent Kresge). I think it's magical back there - I know it sounds corny, but you enter through this winding road that takes you back to a completely natural area. It's just so pretty. You can get married by the lake and have your reception at Kresge hall. There are other options as well. They also have cabins where your guests could stay. However, they have campers during the summer - not sure when your wedding is but I think it would have to be during the fall, winter, or spring.
I know it's not G'ville, but it's worth a look! Best wishes!