EDIT:


RESOLVED!

Thanks for the help, I found one at a shop in Dawnstar.

Mostly its random but there is at least 1 item you can get from a quest but I can't tell you about it in General, you'd have to ask in Cheats, Hints and Spoilers
Best shop to try is Radiant Raiment in Solitude, has the best stock of enchanted jewellery in the game
Apart form that just keep checking every blacksmith and general goods trader until an item comes up

Constantly check out the items in trade vendors, specifically blacksmiths and general goods. Check out http://www.uesp.net/wiki/Skyrim:Mourning_Never_Comes. It increases alchemy.

Moving this to Cheats and Hints

This one because you can also check the blacksmith and Bits & Pieces while you're there. I've also had great luck with Warmaiden's, Riverwood Traders, and the vendors in Riften. Just make the loop.

Go to Radiant Raiment in Solitude, they have a lot of rings/necklaces/circlets.

Since its been moved I'll mention that 1 of the Dark Brotherhood quests, Mourning Never Comes, can get you a useful ring that can be disenchanted for the Fortify Alchemy effect

You can also do the quest Dungeon Delving for Frida, the Alchemist in Dawnstar. She wants you to get the Ring of Pure Mixtures, which has a 12% Fortify Alchemy. Of course if you keep it, you will not be able to finish the quest. The wiki says you can disenchant it though.

I did look into that quest. Unfortunately I looked into that quest. I went to the Hags Cure and the ldy I needed to see wasn't there or hasn't been there every time I go back. So I am thinking I did something earlier to effect that quest.

Thanks, most promising thing I've heard all day!

Funny thing is, I sell almost everything I have at Warmaidens but rarely ever see what he has to sell. Maybe it's worth another look.

EDIT: HAH, I went here to pick up this quest (which I must have done since she didn't offer it to me) and she had what I needed for sale.

Very Very happy right now! Now to Disenchant it. Good thing is, this whole time I've been searching for it I have found all the ingrediants (and much much more) that I need to make all the potions I want.
http://i.imgur.com/GvaBs.jpg

It is a Dark Brother hood quest I beleive, you must be affiliated with the Dark Brotherhood and progress to that part.