This time I would like to review the most used online shops to buy components for a robotic design. Some of them are more focused on the professional market and some others pay attention to the hobbyist.
The two main companies that distribute components for the robotics industry and other engineering projects are RS (https://uk.rs-online.com/web/) and Farnell (https://www.farnell.com/). They are generalist companies oriented to the professional market with a very good client service, lead time and stock. Their search engines are very powerful and one can practically find everything they need. They are very well known in the European market and also established in the American market under other names: https://americas.rsdelivers.com/ , and https://www.newark.com/ . They usually offer free or very competitively priced next day delivery.
More focused on the hobbyist market, one can find RobotShop (https://www.robotshop.com) which has a deep and very well priced stock. It sells internationally. In this shop, the robotics enthusiast can find everything, from ready to assemble kits, to motors, sensors, cables, fixings, electronics, etc.
Another important reference in the hobbyist market is SparkFun (https://www.sparkfun.com/). Almost everything you may need can be found in this online shop, with special focus on electronic components.
If we need specialised hardware like wheels, structural elements, aluminium profiles, etc, a good online shop to buy from is Active Robots (https://www.active-robots.com/)
For an additional stock in electronics and mechanical components, I recommend to check Pololu (https://www.pololu.com), with a good range of components at a very competitive price.
Mouser (https://www.mouser.com/) and DigiKey (https://www.digikey.com/ ) are also two reference shops that work internationally, delivering plenty of products specially for the professional or the engineer. They are more focused in electronic components.
If we are looking for servos or ready to mount kits, we should check out Trossen Robotics, with a wide catalogue for the robotics enthusiast (https://www.trossenrobotics.com).
In addition to previous websites, the engineer or enthusiast should not forget the official distributor of Arduino (https://www.arduino.cc/) and the RaspberryPI official website (https://www.raspberrypi.org/), with tons of information about how to program their widely used development boards.
Depending on the desired component we are after, we can also review the website of the main manufacturers. For example, if there is plenty of budget available and we are looking for a motor, I would recommend checking out Maxon motors (https://www.maxongroup.com), with almost an infinite catalogue of electric motors of all types, electric drives and gearboxes. Other famous brands for the professional markets are Infranor (http://www.infranor.com/) and Yaskawa (https://www.yaskawa.com).
And this is all for now. Enjoy your shopping!