Pricing for a mountain bike?

Ok well my elderly neighbor gave me this mountain bike and since I have no interest in mountain biking i have decided i will sell it, problem is i have no idea what i should sell it for. I will give as many details that i can about it and any estimates would be appreciated! Thanks! Ok it is a Novara Ponderosa the shox say the brand Rock Shox on the gear shift it says Shimano Deore Mega Drive Train and it says its a An6 thousand series AL. Sorry if some of that information is pointless but i figured it might have something to do with pricing.