My guess is that a good dealer can pull off all the stuff to get to the valves, do the value adjust, put everything back in place in about 2 - 3 hours.
In the California Bay Area the hourly rate seems to be about $85 dollars and hour. (Most shops post the hourly rate in the service area).
So my guess in labor $150 - $250 + parts. Likely if you would add an oil / filter change when you open the engine and as long as the have more than 10k miles might as well do the plugs.
common flat rate now runs between $90-$115 / hour.
4 hours on this job?? correctly done, first time shot, will take even an experienced (i.e. having actually done THIS bike before) tech,
a minimum of 4 hours, that is if they have the parts and shims at hand....add in doing an oil change, air filter, throttle body synch, and you add in another hour + or so.
Hazardous waste disposal, and shop fees for oil, cleaning rags, sealants, etc., will add on another $75. Add in the cost for the valve cover gasket (they WILL charge for a new one), plugs, oil, filters, and you have another $160-$180.....
so in the end, the prices they are giving are in line, IF they actually do the services, and replace the parts.
This my friends is why I don't believe a lot of the reports of "your valves are within spec" I hear soo many times.
I have my work area setup with every tool I need, and have worked in the industry doing massive teardowns and repairs, these times are realistic, and don't take into account the distractions clearly arrising in a shop on a daily basis (change this tire, the customer is coming in in 2 hours, and then empty the garbage....)
so, this ain't a simple job, but on the other hand, it ain't rocket science.