There was a reason for not using the Topps backs. The Price Guide cards called themselves Pocket Price Guides. The idea was to put price information on the back and them you could take them to card shows.
I've got the backs from their five years of cards below. They are all of Ryne Sandberg and are in order going down from 1989 to 1993.
The cards list the price of his 1983 rookie card...
1989 - Topps - $6
1990 - Fleer - $9
1991 - Topps - $45
1992 - Topps - $50
1993 - Topps - $50
Those are mint card prices.
An inflation calculator says that $50 in 1993 is worth about $86 today
Recent PSA 9s of his card have sold for around $30. You can buy raw versions of the card for five bucks or less.
The baseball card bubble of the early 1990s has popped.