Pretty much a standard contract for a bare land sale, or vacation property sale. You list with them and pay them 10% on a sale, whether THEY produce a buyer, or YOU produce a buyer through separate effort of your own while under contract.
IF a competing RE company comes up with a buyer, the company YOU contract with will split the 10%, so each gets 5%.
So, your costs are 10%, plus whatever is standard in that area for closing costs. Typically, closing costs are completely negotiable between buyer and seller. Whatever you want to pay, depending on how desperate (read: FAST) you want to sell the property.
I wouldn't have a problem signing that contract, especially if I didn't live in the area. However, I would never allow it to go for longer than 3 months maximum at a time, otherwise they can basically hold your property hostage. If they can't sell it in 3 months, YOU can decide if you want to re-negotiate and sign with them again, or go with somebody else.