[gustomania]

IMO, cards in the 80's generally need to be a PSA 9 or PSA 10 to be in the realm of investment grade (mostly PSA 10's).

Consider the 1984 Marino. There are already 3,000 + PSA 9's and around 350 PSA 10's. In order for this card to make a huge financial swing IMO you would need to own a PSA 10. Any big collectors looking for investment will be in at the PSA 10 price level's considering they go for around $1,000.

Consider the 1981 Montana. There are 1700 PSA 9's and 100 PSA 10's. Still readily available but the 10's are priced over $10K making the PSA 9 a decent alternative.

As a comparison look at another iconic card such as the 1957 Johnny Unitas. In total Johnny U has 2600 PSA graded cards. He has approx. 525 PSA 7's and around 190 PSA 8 and 9 (Total). You can get in around $1200 or so on a more premium PSA 7 of Johnny U that has better eye appeal than many 8's.

So, back to your comparison, I don't see much value in PSA 8's in the 1980's and generally not a ton of value in most 9's. There just not all that rare. I think collecting in football cards from the 70's and 80's is purely having fun understanding that although value may not go down, any modest increases likely wont outplay the market over time unless you invest in high grade and specimen's with great eye appeal. IMO in football 3 of the best investment of iconic cards are the Unitas, Brown, and Namath based on them being lower POP and rarity.

However, that being said, collecting is supposed to be fun and collect what you can afford. As a poster above mentioned many PSA 8's have similar eye appeal to a PSA 9 and can be very enjoyable. I however would not count on them having any significant surges in market price given the qty available of each card.