Max price for both monitor+hardware upgrade? Or just the monitor.
The 4690k is top-tier and will be for many years, don't change that.
8Gb RAM is enough today, but if you have a single stick, you could get another of the same for a total of 16gb.
That means your GPU would be the thing to upgrade, but the 960 is actually very good for 1080p, especially since you have the 4GB version.
My recommendation: Save your money and get a new GPU when new technologies come out. (AMD Polaris, Nvidia Pascal etc.. with HBM and GDDR5X)