If you have a bit of skill with electronics you can make you own micro controllers and replace the Arduino. The partslist is for the simpler controller and you can build it for about half of the cost of an arduino.
Here is the artwork for two microcontrollers you can build for this project.
Simple controller with USB and Jack. This can be fitted inside a Mr Potato Head.
Radio controller with USB, Jack and interface to radio. This can be mounted inside the alarm clock radio.
|28pin 0.3 dip socket||Mouser Electronics||$0.51||$0.51|
|16 Mhz xtal||Mouser Electronics||$0.39||$0.39|
|USB socket||Mouser Electronics
Not needed if you are going to hardwire mouse.
|10k x2||Mouser Electronics||$0.07||$0.14|
|220 x2||Mouser Electronics||$0.07||$0.14|
|15 pin header |
(40 in strip)
|6MM Stereo Jack||Mouser Electronics||$0.80||$0.80|
|9v battery connector||Mouser Electronics||$0.53||$0.53|
The radio controller uses the simple controller parts and the following.
|2N2222 transistor||Mouser Electronics||$0.42||$0.84|
|10k x20||Mouser Electronics||$0.07||$1.40|
|Simple controller parts||$10.06|