The Autonomous tabletops will get to your door quickly if you need you desk top right now, but their higher cost and lower quality don't really match up to make a good choice for sit-stand or fixed-height office desks.
Standalone tabletop for fixed-height or sit-stand office desks, made in China.
The Uplift standalone tabletops offer quite a wide variety of desk top options in size, color, and material for a replacement or DIY standing desk project.
Commodity-grade tabletops for standing desk DIY or replacement
Commodity-grade desk surface for DIY fixed-height and standing desks.