Need Your Help!

So I found a shop, that sells a lot of stones of all sorts, from genuine meteorites, to native american pieces. But in the far end of the back of the store I walked over and saw he had some coins. I bought a 1971 Proof Set for $11, in the box all stamped with S. So when I went up and asked him, he looked as though he had absolutely no idea. He was an older fellow, and he gets up, unlocks the case and grabs an index card, I have no idea how long ago prices were updated but it listed the prices, my 71 was $11. He had random walking libs, some 90% JFK's, and as he's moving some stuff around I see a '69 proof set, which wasn't even on his list that he knew he had. Now, I didn't want to be overly anxioius, because I really don't know a whole lot about these proof sets from older years (hell the only proof set I have is the silver 2011 I got for nephew, that I need go buy one more for the niece). I said I wanted this one because it was my brother's bday or something.... Can anyone help me out on maybe if I'm wasting my time? I do not plan on sitting on these if I can make money, Ideally I'd like to buy and flip, because I'm in the process of buying scrap gold and silver to make jewelry. the '69 was the oldest I saw, after he moved somethings, but who knows... he had up til maybe 2002 or what not? Should I not waste my time? It really didn't seem like he knew a lot about silver at all, and I was quite shocked to find this in a shop selling a quartz rock that was maybe 2'x2' and 6" tall for $1,000 dollars. I know I could google oddball comm's, but I'd like some expert advise as if I'm wasting my time if they're all priced similarly or if I should hop back in there and try and cut a deal? I can be persuasive... I had a lady trying to sell me some charm of sterling silver for $22, I took out my scale and weighed it in front of her, I said no, I will not pay you $22, for 5 grams of sterling silver, which is a mass produced piece made overseas... she was shocked to say the least. I said I'll give you $12 because I know what this cost you... and we agreed. I can show you all a picture of the 71 here in a minute!