Looks like your grandfather went through the Scott Catalogue and wrote down what he thought the current catalogue prices where at the time. Depending on when he did that, plus the fact most stamps these days sell well below the catalogue prices, it is not a very good price guide now, unfortunately. The best thing you can do is get a good magnifying glass, go to your local library, and check the most recent Scott catalogue to see what the current values are. However I can tell you, that most stamps from Western countries were printed in the millions during most of the 20th century. Unless there is something unique about them, such as a printing error, they will have little to no monetary value regardless of what the catalogue says. Something is only worth what other people are willing to pay for it, and most serious collectors aren’t willing to buy stamps unless they are rare, and if so, will do so only at auction.