First reprap Mendel build - got questions obviously

I have done a lot of reading and researched as best i can but i want to ask a few questions before i start buying parts.

So far i have assembled a list of components that totals up to about $250 for all electronics motors and all. I manage a CNC machine shop and have an electronics stud for a maintenance man who should be able to help with soldering up boards and components. So for the plastic parts i plan to machine my own either from plastic or aluminum. I can get all thread and ground polished rod for a great price from my metal suppliers.

I want to make sure i am not overlooking anything or getting ready to buy a bunch of electronics that wont work together. Heres my list so far for the electronics :

Arduino Mega 2650 main board.
Nema 17 bi-polar stepper motors.
Arduino motor drivers.
Fully built plastruder.
Hot end.
Computer power supply.

Aside from the mechanical components is there anything that i have overlooked here?

How do you plan to interface the Arduino board to the motor drivers? RAMPS?

Do you already have a heatbed, endstops, and temp sensors?

Bearings? It seems like most people have moved away from PLA bushings to LM8UU bearings. Belts for the X and Y axes.

Depending on whether you intend to print PLA, ABS, or both you may or may not want a heated bed. I print PLA on an unseated bed using blue painters tape as the surface, it sticks great. ABS on the other hand pretty much requires a heated bed, Kapton tape or glass seems to be the surfaces of choice there.

Welcome to an exciting and addicting hobby!

Forgot to mention the Ramps. I didnt even think of temp sensors. End stops are included with the main board kit, i also have lots of micro switches laying around that are used on CNC's for home out and over travel switches. Thanks.

USB cable?