Here's an actual receipt from the shop I used to do my last valve check:
The shop charges $80.00 per hour for labor. That receipt doesn't reflect the parts needed for a valve check. It also includes the installation of a cam chain tensioner, but that's itemized separately. When I have a valve check done, I always buy the parts in advance and provide them to the shop. Some shops might have an issue with this, I imagine, but the one I use doesn't. Here's a list of the parts and parts numbers I bought and provided to the shop:
You can disregard the cam chain tensioner assembly, tensioner case gasket, and the two cam chain tensioner bolts. Some guys might tell you not to bother buying a valve cover gasket and crankcase cover gasket because they can reuse them. I say to err on the side of caution and get them. If the shop doesn't need them, then you can return them. The reason I buy the parts myself is so, when I schedule the bike to have the service done, all the parts are already on hand, and I don't end up waiting an extra week or two while the shop orders them. I dropped the bike off on the day before my appointment, and had it back the next day.
I've never needed the valves adjusted, but I did ask the service manager what the additional cost would be if they did need it. If I recall correctly, he told me it would be an additional approximately $50 if they needed to shim any valves.
I bought my parts from Rocky Mountain ATV. They've always been a pleasure to deal with. I don't recall what I paid for the parts, but this was in 2021 and I'd guess they're all more expensive now.
Pretty much any trained motorcycle mechanic has done a valve check; shim under bucket valves are the most common kind with Japanese bikes.