Please be careful if you decide to buy a Smoothieboard for your project. There are a lot of clones out there and some of them are poorly manufactured. A lesson I learned the hard way.
When I got my Smoothieboard, one of the first thing I noticed was the fit and finish was rather poor. The female end of the main power connector (for Vbb) did not fit into the male end. The end stop connection points were so close together the connectors did not all fit. One of the connection points was populated with header pins instead of a connector. The list goes on.
Hopefully, the information here will help you select a better one or resolve issues if you have a poorly manufactured clone.
Some of the Smoothieboard clones have alternate potentiometers that give the stepper motor drivers bad reference voltages and the motors won't operate correctly. The bottom image should help you identify if this is your case. A link to a page describing the issue and solution is below, but the short answer is to add the following to your configuration file:
# Fix for incorrect Digipots used on Smoothieboard Clones.
Page describing the issue:
Selecting a Smoothieboard
Unfortunately (in the U.S. anyway), it is hard to find officially sanctioned boards. The Smoothie website has a list of vendors, but the list is short and the U.S. vendor is out of stock (or no longer carries them).
Price is something of a hint. A sanctioned Smoothieboard is just shy of 200 dollars U.S. However, that's not a guarantee, one way or the other, that the board is good. I'm sure there are high priced garbage boards and quality boards for about 100 dollars.
The images below provide some things to look for, but nothing is guaranteed. Research whatever board you are looking at, try to find reviews, and use your own judgment.