it depends on what tools you have, obviously with alot of useful power tools the better stix you can make
usually its about 50-60 for buttons/stix. Using this tutorial where you don't have a router
http://slagcoin.com/joystick/example3.html its about $30 for wood.
Then you have to primer, sand, then paint (bout $6-10)
and other small supplies i might have missed out on (imma guess $10)
so your looking at around $96.00-$120 to build your own custom. Looking at that you can say that multi's customs are really cheap
that website i posted also has amazing information for knowing about building stix