What should a new necro spend 650pp on?

[Castigate]

Wow, I never knew about that Concordance of Research quest, seriously you should fill your bag slots with those and Book of Dark Bindings. Just having lots of bag space and looting a lot adds up quickly when you need money.
For the money you have now, get the 5ac 55hp rings, or an Adamantite Band/Platinum Skull Ring if you find them for around 100pp or less.
Shralok packs are also a good investment, although once you reach the level to farm them in HHP you should.
Also as a Human necro you can wear Flayed Skin stuff which you can find occasionally in EC for real cheap, although most people just vendor it.

Seriously though as a new player bags, weight management, and remembering to loot can be very important. They make all the difference between being broke all the time and unable to afford spells, and steadily gaining cash as you level while getting all your spells.