Neil and janet Armstrong autograph
I have a Neil and Janet Armstrong autograph on the cover of a copy of schematics for the Wright brothers Wright B modified flyer that I inherited and believe was signed during the celebrations For the 75th anniversary of flight in 1978 I am interested in selling but it's not authenticated yet it came from a very creditable source I guess what I'm asking is what is my next move? I've read on here that sometimes it can bring down the price. I would like to get it authenticated but not for $250 and put it in auction but what do I do next I've never had anything in auction nor have I had anything authenticated. Please help any kind of information will be greatly appreciated thank you.
P.s. also if someone could help me to know how to post pictures of the autograph I have plenty thanks