Help - What's it worth?

[notacatfan]

My dad passed away last month; however, before he passed he asked me to take all of his guns (Mom's not comfortable w/firearms). Among his collection is a 1916 Luger, but I've received differing opinions on its value. Long story short - this belonged to either my dad's grandfather or uncle. It's a 9mm, has "Germany" stamped on the bottom of the barrel, "11" stamped in a couple places and "5980" stamped elsewhere. One individual informed me it was worth about $500; another person said between $1500 and $2000. Basically, I'm trying to decide whether or not I should sell it or keep it in the family. Expertise is appreciated!