Sample projects like The Boy and his Kite, needs at least 24GB RAM, or there is no deal. You should target at least 32GB RAM (for AMD 3200MHz DDR4 modules to utilize full capabilities, but you can save quite some money using slower versions).
GPU would benefit greatly having the best your money can buy, nothing with less than 8GB RAM, thou they are expensive as hell nowadays.
For the CPU, AMD’s Ryzen got very cheap motherboards and very cheap processors with lots of cores/threads (need as many SATA or M.2 sockets you would use - pay attention), which will speed a lot your lighting build times, shader compiling times, and if you going to rebuild engine from source code someday that will be greatly reduced as others stated. You should target a CPU with at least 6 cores/12 threads (AMD or Intel, they run at 4GHz+).
For SSD you do need at least one to hold OS (480GB will do pretty well with spare to grow, you can use lower sizes, but you need at least 10% free area to extend as much as you can the lifetime for your SSD). I use RAID 10 hard disk setup (4 x 2TB) which gives 1 hard disk failure tolerance, 4x read speed and 2x write speed with 4TB space == price of 1 SSD 960GB M.2 SATA where I live.