Here is the list of most of my suppliers, lately I stick with Future.
Note however that there may be a 40-200% price difference for some things
Like 74hc283 4-bit adders are 2500 minimum order at digikey but future allowed me to order 25
Future once had the XMOS processor boards at $65 but they were $100 from digikey
Digikey lists parallax boards at $50 but they were $25 at parallax.
Sparkfun seems to have consistent prices.
https://www.seeedstudio.com/ODYSSEY-X86J4105800-p-4445.html
Adafruit
To lay out breadboards you can experiment with
http://en.wikipedia.org/wiki/Fritzing
https://canada.newark.com/ Raspberry PI
Future Electronics – montreal – future is the best with no import duties – this is where I got all my raspberry pis and most of my 74hc chips
http://www.futureelectronics.com/en/Pages/index.aspx?OL=CA&Language=en-CA
Active Components – good for breadboards, wiring and power supplies/meters but I don’t buy components there anymore
Active Tech, 1465 Merivale Rd, Ottawa, ON K2E 5N9, Canada
All the following may have shipping and/or import duties from 20-40% + exchange
I have ordered from all of them over the years
Sparkfun NY – all components
EvilMadScience CA – mostly for LED projects and DIY projects –husband and life team
http://www.evilmadscientist.com/
You can order their cat
Parallax
Parallax CA – parts around robots and their 8-core microcontroller
I have most of their custom controllers and a lot of their propeller boards
https://www.parallax.com/downloads/433-mhz-transceiver-documentation
XMOS
Makers of the replacement of the transputer board – 32 thread – 4 core microcontrollers
digikey – I might have ordered once from them but Future above covers them off
MountainKingTech – I ordered enclosures and a 100’s lot of angle brackets and bolts for connecting boards together
http://www.mountainkingtech.com/
OctoProp Thread (using Pems chain boot method 1 sec/chip)
http://forums.parallax.com/showthread.php?115925-OctoProp-Demo&p=839672&viewfull=1#post839672
https://sites.google.com/site/parallaxinretailstores/home/altimeter-module-ms5607