is Amazon a good indicator of Baseball Card prices?

I bought some baseball cards from an antique store. The dealer had them in plastic sealed packets. Probably hundreds of packets for sale. Each packet contains 50 cards from the mid 1980s to about 1999. I bought 2 packets they were only $1.00 packet. All the cards are commons (so far). On Amazon i see some of these same cards with an average buy price between $.39-$1.40 (depending on card). Here is an example of one card in the packets: http://www.amazon.com/s/ref=nb_sb_noss?url=search-... It is a Brian Harper #391 card. Is Amazon a good indicator of these prices? Because i find NONE of them on EBay or anywhere else. Thanks