mid $XXX in a flea market..... in the real world you should sell it for anything over $3000. Good Luck !
As many said its worth mid to high 4 digit. I think you should preserve such domains for a decade and sell it for upsel cost. Ah, if it was .com, you are sure to hit close to $50K.
$5000 in my opinion. And I strongly suggest you to buy a appraisal from SEDO.com (it costs $30) it will help you to raise the interest of the buyers having a certified appraisal
You have a lucky strike here. My guess is hold on to it for a while, perhaps include some relevant content that may be of interest to a buyer, in which case will add value to the domain as such, also try and increase site traffic statistics, will also add interest. Then put it up for sale, I am sure it will do well, except as already pointed out .com will do much better than .net