A Humanscale solution would be more than twice as much, and I can't find anything else with the raised mouse feature ... is too _high_ for the desk's keyboard tray. I really hadn't realized ...

You’re aiming to have your desktop or keyboard tray at elbow height ... and when it’s raised while you’re standing, it can keep your screen at eye level and your keyboard at your elbows.

There aren’t as many keyboard options for Mac users, but this black walnut tray definitely takes the Apple design from simple to warm and luxurious. If you use your desktop primarily for gaming ...

[Jason Cox] hit the nail on the head, though: add in a couple of palm rests, and you now have four things that will potentially shift and drift out of place on your desk or keyboard tray.