For the most part yes, you might struggle with the bearings. Most of the hardware is common stuff, it just depends how you do it, there are loads of variations. When I priced it up, it was cheaper to buy a kit than to source all the parts individually.
The electronics also depend on the variation. I have one PCB which drives everything. It does the motors for all the axis, the extruder, hot end, heat bed, and cooling fans. It has USB and SD card for loading the Gcode to. There are also 2 sensors which detect the temperature of the bed and the temperature of the hot end and three microswitches for the endstops. That´s all there is to the electronics, it´s quite simple. I use the Melzi V2 controller.