You can't get them by themselves, but the blue servos like the ne in the pic are less than £1 each... You can't buy servo boards without the servo either; that's just called an ESC by that point and tend to be larger and more expensive :L
The potentiometer is the bit with the 3 red wires going to it in this photo :
You can just solder the two resistors straight onto the red wires if you don't trust yourself to solder to the board (you could probably do with a better tip for your soldering iron having seen the soldering in Hogi :L)
Mixing has to be done with a V-tail mixer, which is a pain as they almost double the cost of parts (even though they're only ~£3 :L). The only modding they require is cutting the connectors off and soldering the wires straight to it so they fit better in the Nano...
In other news, I spent much of last night upgrading Scampi... More details later
![Wink ;)](./images/smilies/icon_e_wink.gif)