

This is a chart that shows how much dust you will need to craft your collection expansion wise. (From classic to Rise of Shadows)

This is a breakdown of neutral cards per expansion wise


This is a breakdown of cards of a class( in this case it is druid) expansion. There have been some fluctuation in classes where some of the class cards went to HoF or Hunter was the only card which received 2 legendaries in TGT (Which takes all total hunter legendaries to 20, for others it is 19) but more or less they are quite same.
Expect 8 of more charts like this.

This is a dust wise breakdown of cards of a class per expansion(in this case:druid)
.f you have noticed a pattern then you will that after MSG, Blizzard have reduced the number of neutral legendaries, instead increased the number of class legendaries by 1 (From JtUG).
As a F2P player from open beta I found this new trend more suitable. I have consolidated my attention to a single class (priest) & only craft Priest & neutral cards. After MsG I found it much easier to fill my collection than before.
I have all of the priest cards & almost half of the Neutral collection (with entire adv: CoN,BRM, LoE, ONK)
This is the current numbers of neutral cards I need to complete my neutral collection

From this chart you can see that I fared much better from Ungoro than I did before & I am filling up my neutral collection much quicker than before & because of no duplicate legendary rule it has become more easier if you only concentrate on a single class.
I know that different people might have different experience with this new system but for me this new breakdown was more favorable.