If this is the county or state, you'll spend all your money and they're still going to get what they want. Seriously. I've got a friend here in Florida, who just went through this exact same thing. She didn't win. Cost her north of $150,000 to fight the county. Wasted her money.
It's not necessary to fight every battle in life. Sometimes its better to bend than break. You may think you're in the right in this case and you may very well be, but you're not in the driver's seat.
Take the best offer they'll give you and accept it as progress or move somewhere else where progress won't affect you.
Fighting this with lawyers and your hard-earned money is a no-win situation for you. The county or state has the upper hand.
The lawyers will have your money, the land will be taken anyway and you'll end up right where you didn't want to be to begin with but now you'll be broke.
Good advice, for the most part. There are times though when a hard fight against the odds ends in a win. About twenty five years ago in the Orlando area, my brother and I and a handful of allies defeated a major toll road project. The fight took years, considerable sacrifice, and had many twists and turns, but we eventually won.