[D.P.Johnson]

Anybody been tracking the price history of the 1968 Topps Nolan Ryan rookie card? Just found out my neighbor has a PSA 7 and PSA 8 he bought some time ago that he's looking to sell. Have the prices on this card increased dramatically in the last few years? What is the current going rate for cards in this condition? Just trying to find out what I should offer him for one or both. Thanks in advance.