Need help with my first 3d printer build.

So my big problem is that I’m stuck on which specific stepper motors to buy, and what specific power source to buy for use with the following: Arduino Mega 2560 (clone), ramps 1.4 (clone), five A4988 stepper driver (clones), a 12864 lcd display for RepRap (clone), I have 6 mechanical end stops (also clones) for the ramps 1.4, I’m going to use an e3d v6 hot end (clone), I plan to make a Hypercube style frame with two z avis bed motors. I expect to build it 30" x 30" x 48 or 50", and I hope for a 24" square build surface. This is my first post, I’m not so good with electrical theory vz can someone please suggest exactly what I need? Thank you-