Quick, discount land buyers

I did a search and scanned a few pages back, and didn't find this topic, so I apologize if it has already been discussed. I read this board often, but haven't posted here.

I need to sell a piece of land in a small city in Louisiana, to help offset the costs of some really steep and suffocating medical bills.  It has been for sale for a year, with the only good offer coming from a large national corporation.  It was a deal where everyone in a 1.5 block area sells, or they don't buy.   Needless to say, one guy refused to sell, there was no persuading him otherwise, and the offer fell through.

I have seen ads for "sell your land fast, money in the bank in only days".  I haven't contacted one yet, because I envision it being like dealing with a shady used car salesman.  My question is:  Does anyone here know a ballpark range on how deep of a loss I will take percentage - wise if I go this route vs. waiting an undetermined length of time for a solid offer?

I'm not very well-versed in the real estate business and my terminology is probably lacking.  If I can clarify anything, please feel free to ask. Thanks for any input.