So, I've been using the ninja guide here as a starter however the OP bis link goes up to 570-580.

I heard that the a4s goes along the lines of 640+ ACC.

Do I try to meet 640 ACC as a BiS? Can anybody help me out with what I need to purchase/attain?

At the moment I have

ESO: Weapon, chest, legs
Alex: Helm, belt, glove, boot, jewelry.

I have 500 ESO this week to purchase any other piece of gear.

I don't want to overspend my eso because I am working on a DRK on the side so I don't want to get something that I won't end up using because it isn't BiS

Thanks for any advice.