I write this post to adress the issue that eveningstar challenges are not run very much. and I believe to have a good proposition how to change this.
I will not go into xp/min or amount of resources per run, ill leave that open to others.

First of all, make the ingredients BTA! I don't care if it will take lots of runs to collect them,
but to have to do this for each and every character I roll is a PITA. (Yeah I have a mild case of altoism).

Challenge prices:
Getting random loot type items for supergrind turn in ingredients strokes me the wrong way. As it stands you could make 100s of turnins and get nothing usefull out of it.

The way I propose it should work.
1. you farm for ingredients
2. you turn in, choosing a <gear type> (longsword, lightarmor, enz) and <base lvl>(16/20/24/28).
3. you get that cormyrian<gear type> of <base lvl> with a random T1 prefix/suffix.
4. you like the prefix/suffix -> goto 5.
you don't like the prefix/suffix: you can now choose to change the T1 into another for 50% of the price for the base one.
example you want acid but get flaming, now you spend resources to change flaming.
if you are lucky you will get it first time, else youll have to "reroll" your item till you get the T1 you want.
5. you spend ingredients to get T2, this will lock your T1 and give you a random T2 upgrade.
6. you like the upgrade -> goto 7
you don't like the upgrade: you can choose to change the T2 by spending 50% of initial cost in ingredients again till you get the upgrade you wanted.
like the T1, you can get lucky and get it first time or you will need to change it till you get the one you want.
7. you spend ingredients to get T3, this will lock your T2 and give another upgrade.
8. you like the upgrade -> goto 9
you don't like the upgrade: you can choose to change the T3 by spending 50% of initial cost in ingredients again till you get the upgrade you wanted.
like the T1 and T2, you can get lucky and get it first time or you will need to change it till you get the one you want.
9. you spend ingredients to get the final T4, this will lock your T3 and give another upgrade.
10.you like the upgrade -> goto11
you don't like the upgrade: you can choose to change the T4 by spending 50% of initial cost in ingredients again till you get the upgrade you wanted.
like the T1, T2 and T3, you can get lucky and get it first time or you will need to change it till you get the one you want.
11.you spend X heroic comendations plus some ingredients to get +0.5[w], +1 enhancment and get an "augment-slot"(blue for armor, red for weapons).
(maybe "spellplague"could be added also?!?). This will lock your T4.
12.your cormyrian<gear> is done.

This way it would still be an enormous grind to get the item-properties you want(unless you get lucky and have to spend less),
but at the very least you will have some control about what you are going to end up with.

I think these two changes will make the eveningstar challenges viable to run once more.

Thank you for reading.