it's always cheaper if you bring someone the part, already removed. It saves them the time of removing and reinstalling.
I would guess they'd charge an hour of labor to clean?? The reality is that is doesn't take an hour to clean...and it is actually very easy to do yourself (hint, hint)....
There are so many youtube videos out there about cleaning scooter (GY6) carbs...it is not difficult at all. If you are competent enough to remove your carb from your scoot for service..you already have the skill to then clean it!
What is wrong that you think your carb needs cleaning? (all carbs do at some point..just wondering if you have a specific issue)