Value, if you have good marketing skills and if the bike is clean and in road worthy condition - $100 to $200 US. If you are patient, $150 - $250 US.
If you decide to keep and ride the bike, be prepared to at least - replace brake pads as they tend to harden with the passing of time, open up and grease the bottom bracket, head set and wheel hubs. That is the minimum. You might give some thought to replacing brake and transmission cables also, but not absolutely necessary. Those items will set you back about $30.
Now, to be safe, replace the tires since, once again, the passing of time will negatively impact the integrity of the tires strength, perhaps allowing for a blow-out while riding. Most of the time a flat causes pain in the butt (figuratively speaking), however; a nasty and sudden tire pop on the front might cause both you and the bike considerable crash pain.
If you have to have others do the work, add $100 at least to your clean up and make road worthy costs.
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"98% of the bikes I buy are projects".