Here's some advice, and I think it's a concept MOST PLAYERS ABSOLUTELY NEED TO START WRAPPING THEIR MINDS AROUND:

Drop your prices. The item not moving, even after 20 minutes? Keep dropping. And dropping. Advertise. When you finally get a sale, understand that this is the "new" value of the item to you. Don't be discouraged -- just stop kidding yourself. This is the only solution.

A glut of supply and low demand means that your items are actually worth less. So many people still trying to get "old" prices like, say .... 1200 for a swordstone or something .... they must be getting so frustrated, because they have such a skewed perception of what the value of their stuff actually is.

Here, try this: pick the 3* material with the highest quantity in your inventory.

Check the average price for the material at clockworkmarket.com. Also watch the other offers for the same material in trade chat. Now, undercut that price by at least 20%, and do so LOUDLY. And a LOT. In say in the most crowded areas you can find, and in trade chat. You'll dump your wares, trust me.

No, this isn't caving in and getting less than what something is worth. I can't stress this enough -- all you're doing is acknowledging reality, and coming to terms with the fact that your first exposure to the price of certain materials occurred when there was, say, 20,000 iterations of that material gamewide. Now that there's 200,000, your perception of the value of that material needs to adjust, or you'll be clinging to it forever.

Realizing this and mentally forcing myself to look at the situation rationally is all that's worked for me. I've made about 70k crowns in two days, just idling for a few minutes between clockwork runs. All I've done is made myself willing to readjust my old perception of what things were worth. It's better I have the very useful, very liquid cash than the very useless, very dust-gathering pile of 5,000 unused mats sitting in my inventory.

Here's another minor tip to clear out some of those mats. I've found it works for me:

Look at your recipes, even the really low-star items, and find what you have the materials to make right at that moment (meaning, probably nothing that requires a leveled-up previous version of equipment). Convert the CE cost to crowns (in terms of the going rate), add in the direct crowns cost, then throw in an estimate of the value of the materials involved as best you can. Then, advertise to sell a premade of that item AT COST. By that, I mean, don't attempt to mark up the price of the premade simply because you made it. Rather, consider it as nothing more than a method to make a sale of the materials involved, and an easier way to move them than trying to push them on the market individually. Don't attempt to make a profit beyond that .... you'll be shouting until you're hoarse with most items. Only very, very in-demand items will still move at markup in this economy!

It may help to stress in your ads that you make the item to order, and you'll give any UV to the buyer.

@jeburk Except that they used mist energy and looted the mats so the item cost them 400, which means they also just netted the same profit :)

Also, when I "wtb" I list it in semi bulk at a very low price and eventually somebody sells me them. That's why I say it is a buyers market. If I want a price for mats I almost certainly get them.

I recommend dukelexon's post if you want to sell more than 1 - 2 mats a day. He has the real grasp of why is going on here.

Actually, dukelexon's advice on advertising loudly, is a good way of ending up on a lot of ignore lists. It is better to just advertise clearly, with conservative use of Caps and special characters.

[Disclaimer]
I'm still trying to make money for my 5* stuff and obviously don't know THAT much of the real secrets to piles of crowns, but a few tips that you could easily try to get some business.

-Trade is spammed? Even general is spammed? Stand at the Arcade alchemy or Token Alchemy machines and /say. Of course, don't go all out spamming or you'll end up ignored.

-Have something people would be interested in. Or, if you're selling not-so-desired stuff, round some numbers off, offer a bulk discount, throw in freebies. Make the deal attractive. If they don't buy your first package, they might ask about others.

-Undercut to a point. I know this might sound counter-intuitive, but rampant undercutting, especially in a short span of time, ends up hurting not only future sales, but yourself. You don't want to be the one who does high markups. You also wouldn't want to be the one to be seen as trashing the economy.
UNLESS
You have no trouble getting the rare stuff you need yourself and are already dripping in mats. But if you're posting here about the issue, chances are you aren't a part of the pros :p

-Be patient. And I don't mean keep waiting until someone finally agrees to buy your one and only 4* item for [price that wouldn't sell]. Probe a bit if you're unsure, but don't be thinking "rawr u needz mah [insert mat name] cuz iz supa rare lololol so i sellz expensiv!" Chances are, someone else has a stock of them waiting to dump.

-This next bit probably requires more effort. Know some of the recipes. If someone just advertised green shards, there's that chance he might want monster bones/critter carapace/bushy tail. You get the idea. The more specific the need, the more likely it's to make something. And sometimes, to get that item made sooner, people might be willing to splurge more to speed up the process. Grab that opportunity if you can.

In before the leet players come in and "lol dabian your advice sucks your gear sucks". /Paranoid dun-tase-meh-bro look.

@jeburk:

Two things,

In my experience even your listed prices are pretty high. I will only pay a max of 17cr for shards and 25cr for 1* mats and never had any trouble finding sellers at those prices. The 2,3, and 4 star mats have more variability since the strata of the popular gates make some of them more popular than others, but it's not uncommon to see people struggling to sell their 2* mats for 100cr a piece, and I've bought tons of them at 50cr a piece.

Also, I wouldn't be too sure about the profit you're going to make on that owlite shield. I would be quite pleased if I could sell 2 star equipment at 2000cr a pop, but at those prices people just don't want to buy, I typically have to go more toward 1500-1700 to get a sale on different pieces of 2 star gear.

Remember in your valuations people, that mist energy is not worth the same level of crowns as crystal energy (and why would it, you can do a lot more with CE than ME). This is why it is so hard to make a profit selling or crafting 2* gear, because the recipes aren't that expensive and people can just build it themselves using 12 hours worth of ME and save 2000 crowns, if you don't happen to have the free time to clockworks dive for a while then using that ME is effectively free.