Taking the age into consideration I would say mid xx to a reseller at most.
You must remember, you cannot take the listed price of other extensions as any basis for appraisal on yours. If another extension has sold for a certain price, then yes you can use that as part of the appraisal technique.
However, the price a domain is listed at in no way reflects it's value. I can easily register BuyMyPoorDomainForAHugePrice.com and list it for $10000 sale price, but does that reflect in any way the value of it? If you look at most domains, the listed price is far beyond the realistic value.
That said, due to the age of the domain I would suggest keeping it, developing and bringing traffic. The age of a domain does increase it's value, but an aged domain with good traffic will have good value.