To easily mount the sensors it is HIGHLY recommended to use the cheap solder paste method on a hot plate. A toaster oven can work, too. Even any fry pan on the stove top can work but check with the boss first. Getting the sensors well-mounted is crucial. After the flux burns off (about 7 minutes on this hot plate) a perfect silver solder job remains.
The sensors and the Arduino board are worth shopping around for. Buy the rest from one source. The trick is to minimize shipping costs. The LCD and the small parts can be found at a decent electronics parts store (be sure of configuration compatibility for the potentiometer and reset push switch so they fit the board). Ordering from Digikey.com is the easiest and it beats running around looking for small parts.
An Arduino usually has a bootloader on it. When using one of the hex loaders you may or may not be loading or even overwriting the bootloader. That’s fine, it just takes up space, unless you are trying to load something from the IDE. Then the board needs to have a bootloader. Fortunately, the IDE has an option to first load the bootloader.
Sometimes DigitalCarbSync hex programs are supplied with and without a bootloader. Either will usually work. Sometimes the supplied hex program is too big to load directly if it also includes the bootloader. Just use the other version.
Here is some useful information about the bootloader.
You may be better off buying directly from our source. They have lots of options.
It all depends on the number you want, shipping costs and convenience. If you are buying a board from us the shipping is flat rate so adding on the connectors may make sense.
These Luer connectors work. You can mix and match the sizes.
Here’s what we use: