Don't forget clock chips & crystals, or modules.
Also decent shift registers, from the TCIP6x595 line, for working with 12V LED strips.
Logic level MOSFETS, good ones with Low Rds, low gate capacitance, N & P channel
Current limiting resistors.
100nF caps
parts to make standalone arduinos: blank chips, sockets, perf board, 16 MHz xtal, 22 pf caps, 10K resistors, 1N4148 & 1N4158 diodes, low dropout regularors, 5V switching regulator wallwarts.
LEDs.
LED matrixes
AVR Programmers