If we talk about Czechoslovakia, recently I discovered this one item and say "Hallelujah again"!!!
Great-great-great design, great graver job, great feeling just to look at this sheet of four, and You can even feel it on Your finger when touching this stamp! Which perfect color in use, it stay in brain memory for long time! I know this issue long time ago, but when You deal with lot of material, sometime it will stay unnoticed - that happen to me, I remember it but didn't "touch" it! And now, when I have this sheet of 4, I really discovered true value of philately and value of "good investment" in this "dare" time of recession and bleak future - simple, it made me happy!!!!
Catalogue Michel (2001-2 edition) have an value just for complete set for 8.50 euro, and stated that set have sheet of 4 and sheet of 10 stamp on. Prices for complete 6 sheet are not big, just 70.00 euro, on market you will find it for 70-80% catalogue value, but Czech catalogue separate this sheet in two section, of 4 and of 10 stamp, that are also available on market.
Because quantity printed and time that pass, it made it more hard to find, it is printed from 1/2 mil to 1 mil pieces, that are relatively big quantity, but - still it is hard to find.