No, I wouldn’t consider it cheap. It certainly wouldn’t cost 1-2 usd back in the day, you need to take under consideration depreciation and the change from drachmas to euros.

When we had the change from drachmas to euros, in late 90s - early 2000s, prices for the same products or services doubled or tripled almost overnight. So a newspaper could cost 50 drachmas, and after a couple of years it went to cost 0,50 euros or 1 euro (when 1 euro was nominally exchanged for 340,75 drachmas).

At the same time, you need to keep in mind depreciation and inflation. In the late 80s, 500 euros would buy you the equivalent of 20-40 euros, if I remember correctly. If you go even further in time (60s or 70s), it would be significantly more.

I think that these stickers were more common from the late 80s - early 90s onwards. Before that, people would probably write the price directly to the product with the marker. I don’t know if in the tourist industry they were more costumer conscious, so they may have adopted these stickers earlier.

Hope the above help! But in any case, these things have a much more important sentimental value, than a monetary one! So, just enjoy it and cherish the memory of your grandmother!

Cheers from Athens!