Generally you can buy any Arduino board on the internet and they will work out of the box, this means that you can find many suitable development boards at reasonable prices on the internet if you are prepared to buy from lower cost countries such as China, this is because the actually designs are open source so anyone could technically make their own boards.
Some people say you should support the original source and buy from the Arduino store, fair enough but sometimes you will see a variation which improves the original design, lets take a look at one of these variants and look at some of the differences
keyes UNO R3
This board has a few nice features that I liked
1/ The ability to switch between 5v and 3.3v operating voltage, handy for 3.3v modules
2/ 3 leds for power and more importantly TX and RX
3/ You can see that there are nice headers with GND, Vcc and SIgnal connections. Very handy for connecting sensors as many modules and sensors use these 3 pin type connections. Saves buying a sensor shield.
4/ Cosmetic changes such as different positioning of the reset button, leds moved to edge of the board (so you can actually see them when a shield is fitted) and the usage of a mini usb connector
5/ Wider input voltage range, can go up to 23v input due to the usage
So as you can see with this variant there are a couple of features that could make you use this in your projects, my particular favourite one is the coloured headers which make it easier to connect sensors and modules and effectively get rid of the requirement for a sensor shield.
What's nice here is that someone has taken the original design, tweaked it and made some improvements and then released the product.
I picked one of these up for about £5.27 from Aliexpress, worked out the box and you'll see it in use in some later projects
Links
keyes UNO R3(red) MEGA328P ATMEGA16U2 Compatible for Arduino
