I'll tell you this: If you have more Angel Feathers or Gold Bullions than other Rare item (in my case it's about 6 Rares, including Book of Fire), you know your knuffels are collaborating with Alchemist and you're gonna need the material next time you take a quest XD
Of course I'm exaggerating, but yeah, that's the algorithm

Hello, may I buy 10 x Crystal Ball please?

Oh, honey, you don't buy those, you just get them XD Sending trade

5 x Angel Feather, 44 x Green Balloon, 42 x Shell, 17 x TikiTaki Tribe Mask, 20 x Valerian Leaf.

I need these items C:

This quests are killing me.... >.<

Well, at least you need one material I have for free, so that's saving you 200
If the quests are killing you, maybe it would be wise to take a short break from them to take some breath?
Sending trade

nuuuuuuuuuuuuuu i want to finish them all!!!! lol :3
i just need all my knuffles to be 100 so I can dig better C:

Okay, I can understand that
Yeah, all knuffs at 100 is helping a lot. But it's also important to have similar amounts of each element. I have too few Fire knuffs for example

Yeah, having a lot of high level knuffel does make digging easier.
That said, Umiel now decided it was time to ask me for 2 earth rings. Let that now be the one ring my knuffels are bad at finding.
May I buy them from you? :}

Haha, sure

Thank you.
First i even checked my mule account but there were none of them there either. Still I love doing quests, so. :}