Jafos yurt is 30' d.
Alternative to insane thousands of dollars a little 16' platform is gonna cost now.
If you have a flat lot pour a slab.
But I wouldn't do that myself. For a little 16' yurt, I would just prep a flat spot and erect the yurt on a poly tarp. Fold the tarp edge up outside the wall, under the cover. Think 'bathtub' floor. Add a low tension band to secure the tarp to the wall. Lay indoor outdoor carpet inside.
If you have a sloped lot, and need a bonafide platform, Pacific has excellent deck plans. But the labor and material is gonna be upwards of 10K right now, IF you find someone to build it.
Here's a what for. Last I checked three months ago, 5-2x4-8' studs was $100 including tax out the door at home depot. Those same studs were $25 June 2020. A framing load of lumber and trusses for a small 1800 sq ft. single level tract house was 28K a year ago. Now it is 85K. I just got that number from a builder whose house I was trimming about three weeks ago.
Pacific might have leads on an erection crew.
btw I built my 16' d wood
for ~$650 in 2013. I built a barn shed on the 16' platform last summer. Right now that little 10x12 shed would cost 10K in materials. Anyway there you go. Good luck.