All healthy so all magicka enchants on gear to make up for that some. Haven't been able to get magicka willpower jewelry yet. I'm using max health/magicka buff food that I craft. 5300 health/4900 magicka. So 18k health/31k magicka while buffed. It's a sharpened destruction staff I found but isn't a set one or anything special.

I'm not having any sustain problems on my magicka DK (at least until the Morrowind patch comes out and they make sustain issues worse). Here's what I use. Not saying it's the best set-up for DK ever, but it's working for me so far in PvE. (I'm sure someone out there will pick it apart and say it's a terrible build, but it's good for magic sustain, at least, and her surviveability is good as well.)

A matching magicka jewelry set (Vampire Lord, I think)
5-piece Seducer armor (reduces the magic costs of abilities)
The rest of my armor and weapons are Julianos (raises max magicka and spell criticals)
5 armor pieces are heavy, the other two medium. (But I would change the medium armor to light if I needed more magicka.) All are either purple or gold.
Roughly half the armor has health enchantments, and the other half has magic enchantments
I use food before every fight that boosts both magicka and health at the same time, but you can also choose food that only boosts magic, and get more magicka from it.
I have 91 CP points into The Magician (reduces the magicka costs of spells), which will be destroyed with the Morrowind patch, so BOOM! There goes my character build. LOL.

All my attribute points are in magicka. She's a Breton, so she naturally has boosts to magicka, as well.

I hope this helps in some small way.