Don't go tooo overboard, a lot of microcontroller experimentation can be done with just a handful of different resistor values, and just a couple three capacitors. Every value in the catalog is not needed. Search this forum, there was some discussion along these lines not long ago.
Just my $0.02, but I'd go for:
330?, 1K, 2.2K, 4.7K, 10K.
100nF multi-layer ceramic caps (MLCC), 10uF electrolytic, 16V give or take.
LEDs, 5mm or 3mm, various colors to taste.
Tactile button switches.
Diodes, 1N914 -or- 1N4148, and a few 1N400x.
Transistors, 2N3904 (NPN) and 2N3906 (PNP) -or- 2N4401 (NPN) and 2N4403 (PNP)
555 timers are nostalgic and fun, but I seriously have little use for them these days. Still, a person may as well have a few to play around with, as they're very inexpensive.
Dip Micro has a lot of these basics and very reasonable prices.