Our normal distributor each chip is $0.24 per 100 with shipping not included. Also a lead time of 2 months with our PO system (snail mail) and shipping (UPS ground). Overall we order about (5000) NE555 per year, so if we switch over to China we would save about $700 per year, but the catch is you need an ebay account and a credit card, slim chance of that happing.
I tested all of them in a astable mutivibrator circuit with a 97% pass rate, 3% failed with voltage output issues, they did oscillate at a frequency but at a diminished voltage. A 97% pass rate is fine for what we do, all of our designs we add an IC socket so if it fails it's an easy swap. Also our circuits a novelty items (buzzers, LED flashers, etc.) and laboratories, there not in high reliable systems / life support or in safety systems.
One chip I tested was really strange. It ran about 40 times higher frequency that what the other comparison chips in the circuit. I placed the chip in the circuit a half dozen time and it came back to life, really weird.
I set up a zif socket and a few resistor and caps, 2K, 1K, and a .1 uF cap and a 1uF cap as a filter cap on the supply.
ZIF Socket Bread Board
Bad Signal The 3%