The starting point will be the comps. Ultimately, the property is worth what your buyer is willing to pay for it, when it's made available on the market. Finding that best buyer, however, will take a good planning and execution. So the real question is whether you'll risk to do it on your own (FSBO or relative who happens to be licensed) for a full-time dedicated realtor to get the job done right, leaving no regrets behind.
In any case, I wish you the best of luck!
Intero Real Estate Services
DRE # 01859971