it depends on:
- where you are (shipping, import duties)
- what products you want (some distributors don't carry all products)
- How many you want
In the USA, digikey is big but I much prefer mouser (mouser.com) because their small quantity prices are much better than digikey. I don't know what their international shipping costs are, though. Mouser doesn't carry National parts, though.
there really is no one good answer. I use a multiple of suppliers. Here is my list, by order of preference:
- mouser (mouser.com)
- glitchbuster.com
- all electronics (allelectronics.com)
- the electronic goldmine (goldmine-elec.com)
- circuit specialists (circuitspecialists.com)
- digikey
Of course, these are all based in the USA...
Phil