I believe the first two runes are for 10 and 12 slots, not 8 and 10.
minor rune of holding for 8 slot 4.95 silver – actually 10 slot bag??
rune of holding for 10 slot 14.80 silver – actually 12 slot bag??
This has so far not been an issue for me although I will say silver/gold is tight and I’ve had to sell/farm some mats a few times.
However, the larger runes don’t look to offer great value for money I must say!