All depends on your budget. The super cheap desks are wobbly and not designed well. More expensive desks are sturdy but run up in the $1000-3000 range.

A lot of people opt for getting the legs they want, but then go to Amazon or elsewhere to get a desktop.

Then there are accessories to consider, like cable management options, computer and monitor mounting options, etc. That can add a decent amount of cost to your setup.

Standup Desks

• https://www.evodesk.com/
• https://www.vari.com/desks-and-tables/
• https://www.fully.com/standing-desks/jarvis.html
• https://www.upliftdesk.com/
• https://desk.haus/

Tops

• https://www.amazon.com/dp/B08BZL6LWJ/
• https://www.armanifinewoodworking.com/
• https://www.hardwooddesktops.com/

Be aware if you order a separate desktop, you might have a more difficult time putting everything together. You will need to predrill holes, and consider if you want to use threaded nut inserts which allow you to more easily take the desk apart many times, in case you ever need to move it. It's more time and effort, but might be worth it to some.