Additionally, if there WERE some way that you could get "your guy" anytime you wanted, there's still no way you can guarantee that he isn't tired, or injured, or super-busy, or pissed that he scratched the new Volvo while on his way back from lunch, or too focused on the exploits of the North Korean Olympic Short Track Team, or just 'not mentally there' that day....
I've said it before and I'll say it again: The whole point of the Sparx is that it takes the unpredictable human element out of the skate sharpening equation.
For people like you (and me - I'm in Southern California), who happen to live where "good" sharpenings are harder to come by, that's a HUGE benefit. For others that have ready access to quality sharpening, maybe it's not such of a big deal. But, simply not having to worry about it is what makes a Sparx worth it for the hundreds (thousands?) of people who've purchased one.