It's back up now. I just went to check what the most expensive character you could make was (I have the vampire book downloaded but none of the other ones), and it turns out the vampire book was all I needed. Taking a non-aligned decked out vampire on a zombie dragon (with the curse of the blood power) clocks in at 1560pts (actually you can make it 1570pts by taking both heavy and light armour which although, I believe, is techniquely legal is highly pointless so I didn't include it). This total turns out to be the same if you take a decked out von-karstien vampire on a zombie dragon. Other honourable mentions for being ridiculously expensive single models were a decked out father of pestilence (which is the most expensive non-combined profile model and the most expensive non-vampire model) at 1470pts. Also pretty much every bloodline decked out on a mount clocked in at over 1400pts with many being over 1500pts.
Please don't ask me why I bothered sifting through armybooks to calculate this.