You could get 1x8GB Memory Stick, a long with 1060 6GB / RX 480 8GB versions of GPU, but it will raise the cost up to 700.
Notice - Some Intel B150 chipset motherboards may need a BIOS update prior to using Kaby Lake-S CPUs. b250 is an option here, but it will cost +20$.
i'd pick this build with 1x8gb memory stick (leave you free slot on motherboard to throw another stick for 16GB total), with GTX 1060 6GB . For the first upgrade i'd add SSD and another 1x8gb of memory.