I am going through eminent domain/condemnation in Minnesota for 13 acres the State took for a widening an existing highway. They took the land in October 2005, still not settled. In MN, the State allows you $1500 to hire your own appraiser. SC should have a similar program. In my case I lost 3 25' Black Hills Spruce trees. The State offered $1200 each. Also check to see if your property survey shows you own to the center of the road. There most likely is a perscriptive easement (some past owner sold the State the right build the road in the first place) but check to see if there is one, and if there is one, check to make sure it was recorded at the local county when the easement was first put in place. If no recorded easement, you make have more property to sell.
In addition, you have right to severance damages if in any way the taking harms you; loss of the trees, loss of front yard space, more noise/light pollution because the tree loss, reduced property value for the remainder, increased traffic/safety issues, etc. Focus on damages. Getting a big price for the small parcel could be used to value the rest of your property at a similar price ( my experience).
Are any of your neighbors losing property to this road project? If so, get together with all of them and strategize how to get the best deal. Perhaps one of them is losing a much larger piece and willing to go to the mat with the State. They may be willing to share resources with you. Don't be the first to settle. Learn from those who preceed you. My highway ownership group successfully convinced one neighbor, who wanted to settle right away because of the perceived hassle, to wait until others had "taken the State to the mat". Their original offer was $13k per acre. They settled their taking for $145,000 per acre plus interest paid since the taking (MN 4 to 5% per annum).
Educate yourself and don't take the State people for dummies. They have alot of experience with this issue.
OrangeGuy