Well, finding things to spend money on itsn't hard. I've already got planned out what to spend the next 400$ I can get on. Of course, 300 of it is just for the Dino 3x3. I don't think You will have any trouble finding things to spend money on, I just whish I had money to spend on cubes.
I would recommend looking into the Fangshi Shuang Ren, but I'm not sure that amazon would carry it. It is also yet to be released, so you would be pre-ordering it.
If it were me, I'd get a wittwo, rex cube, curvy copter, mirror cube, void cube, SS 4x4, and SS 5x5. I don't know what cubes you already have though, so just choose whatever you want.