My estimates show about 5 hours for the assembly time, so unless you get paid $1000/hour, this is not going to cost that much =) As for the time invested in software and hardware development - yep, it takes time, like any project is going to.
Therefore while it's a great tinkering project I'm really sceptical about the actual value this could have for "end users" unless the value is the tinkering itself ;-)