Lemme chip in my two cents here...
As a brand-new (but long-time admirer) Dark Eldar player, the units I will be prioritizing are warriors, wyches, raiders, and the archon. It's your basic 1 HQ and 2 Troops slots, with a transport or three thrown in. After that core group, I'm going for Incubi (f-ing bad ass), reavers, and hellions. The ravager is a bit too expensive for just starting out, and the mandrakes are sweet models, but a little underwhelming game-wise. They're a latter purchase. The special characters I'll have to wait and see on. They look AMAZING, but the Urien guy benefits units that don't have models yet, so, ehhhh... and Lilith, she, uh, ..., damn, I think I'll buy her too. Shhh, my darling bank account, shhh. It'll be okay.
Also, if you could restock some of the older models, like the scourges, talos, and haemoculi, and any other special characters that don't have new sculpts, that'd be cool too.
Oh, and codexes. Lotsa codexes.