It could be a valuable bow, because it appears to be in good condition and Black Widow bows have been in demand for many years. I have had 6 of them over the years, and have 2 now that I don't plan to sell. Or it could be worthless, depending on one thing: limb twist. You should use a bow stringer to string it, and make sure the string loops are securely fastened inside the string nocks on each end of the bow. Pull it to half draw a few times to make sure the string is seated in the string nocks. With the bow strung, put one end on the floor with the other end cradled in the palm of your hand. Raise it up and down until you have a clear view of the string passing over the string grooves and on down the bow. The string should make a straight line as it passes over the string grooves. Look from both ends. If it doesn't make a straight line, it may have limb twist, which could be permanent or fixable. Take the bow to someone who knows what they are doing to see if it can be fixed, because nobody is going to want to buy it if it has limb twist.
Once you ascertain the value and accumulate enough posts, you could sell it here. Or, you could list it on Trad Gang. Trad Gang members are probably more oriented to classic wood bows than here, but both places should have members that are interested in this bow.