As I feel helping situation, here is break down what would be cost of tiering up runes if start rune is T3 (most of us would use those). Not, this is simple tier of the same runes. In the order to get something useful - you have to have multiple runes of the same tier. So for example, to make Advance X rune you need: Magic x 7, Resistance x 7, Endurance x 7, Mind x 4, Vitality x 2, Vigor x 2 and Quickness x 3. So if you like to get T10 - that is 4064 AT charges to prepare rune, another 31 charge to combine them to get single Advance X.
Even at that brake down it would cost much more to make them then to buy finished one from cash shop, but this will also allow new player to experiment and get some runes before reaching end game, thus more AT charges sale, and once they see how much takes to process, they might just opt to use CS rather then go trough all work to get simple rune.
This would make rune transmutation really a part of the game, and allow everyone to do it and use it. AT charges would be used more (thus more $) and runes in AH would be finally worth something. (at the moment I just NPC most of runes from the game - it is just not worth to bother to post them in AH)