You can now get a board with all the electronics from Rugged Circuits for $10.
If you want to have a circuit board made you have to DIY or send it to a "fab house." These services require design files in a compatible format. "Gerber" is a common format that the Eagle software I used outputs and just about every board manufacturing service accepts.
The Gerber files I used are attached to this step. You can also get the Eagle Files from GitHub and make your own Gerber (or whatever) files if you need to modify the design. You can send the Gerbers to a fab house like BatchPCB or www.sunstone.com. I have used both. BatchPCB will cost about $13 not including shipping for one board and it will arrive in about a month. So far they have always sent me 2 boards when I ordered one, but I have had one board (of the two) have problems. Sunstone's prototype service costs about twice as much and you will have boards in half the time. I quality of the Sunstone boards is good, but the silk screen isn't as clear as BatchPCB with the same Gerber files. The price at Sunstone is the same for one or two boards so go ahead and get two.
If you want, you can order boards from BatchPCB via files I have already uploaded here.
(For the adventuresome an
If you want to modify the design and make your own Gerber files, Spark Fun has a good tutorial and job file.
You can upload Gerbers to BatchPCB and have their DRC bot check them for free, Sometimes the design rules in Eagle show problems that you can ignore, but the "DRC bot" there rarely has false alarms.
There is also great, free online Gerber viewer here: http://circuitpeople.com/