I would keep it. I'd quit my job and buy a nice big boat. And then probably have to find a new job to pay for the upkeep on the boat.
As tempted as I'd be to keep it, I'd probably be too worried over where it came from/what might happen if the person(s) who 'lost' it found out I had taken it. Paranoia courtesy of hollywood.
This conversations reminds me of the boat captains who would find drugs floating in the Florida straits... 5 bales of pot, each weighing 80 pounds, that's 400 pounds of weed. Notify the coast guard that ya just found 3 bales floating! and pay your boat off with the rest. That was pretty common. One of the captains that I worked for would make us videotape the bales floating along and subsequently slashing them open and sinking. He didn't want it being brought on board and didn't want to be accused of taking any. One of those bales coulda paid for my college and then some.
Actually, I'd buy the Lions, and spend the leftover money on WRs.