I am building a 200 x 90 outdoor. FWIW, on a very similar site for a 200x70 ten years ago it was significantly cheaper, just as a caveat to PNW. 10 years ago you could do a 200 x 70 (here) for around 10k (grading, rock base and sand). Anyway, this ground seems relatively flat to the eye and I was using it as a DIY grass arena previously. Both bidders would use laser grading. Contractors are extremely busy and it took months to even get guys out to bid.
This is for ground work only. Both excavation companies believed a crown would be counter-productive on this site, or would require more extensive drainage:
First bid was $6,000. This was for a 2 degree slope on the short side and compaction. They did not include any drainage work on the quote, and it was just a quick visit to the site.
Second bid was $11-12,000. This was for a 1.5 degree slope down the long side to the natural drainage area and a 1 degree slope along the same short side as above. They came twice, second time brought out the laser to check and spent several hours at the site determining the best location. They determined the arena should be pushed out 20 feet from where I had planned to put it and further back on the long side too to allow for a 20 foot drainage swales along both long sides and to take advantage of the best areas for drainage. The bid also includes bringing back top soil to the swales for seeding grass (I provide seed, but they will pack it). They do not have a 15 ton roller, so that cost will be additional.
It took 4 hours to remove the topsoil on 200 x 90 with a dozer, so if you just wanted that done, you could probably figure $175-250 an hour plus whatever they need to make it worth the trip. It would have taken a skid quite a bit longer.