1. Dig a level area, about 24x20', to a depth of about 4 inches (for the court tiles kit I used, there is also a 30x30 option) https://www.rubberflooringinc.com/int.... Got help digging by an employee of Casa De Maryland https://wearecasa.org/. He also helped with the gravel step later, so I estimate his total labor cost to be about $800$1000. We have 20 steps to get the gravel up, so if you have a more direct access it will be easier. Be prepared to do something with all the dirt you dig up, we have a 3' high line of dirt along a fenceline right now.
2. Build a wood frame to hold the gravel. We used 4x4s, but 6x6's would be stronger but more costly. the top of the frame should be level all around, and corners square. amount of wood you need depends on slope of your ground. 3 sides of ours was just 1 piece of wood, but another side was where the ground sloped off so we had to build up 3 pieces of wood high there to stay level w other sides. We spent $300 on wood, delivered by TW perry. get pressure treated for outdoor use.
(optional step we did not do, rent a rolling compactor from home depot to compact the ground you dug, we used a hand tamper seems fine so far)
3. Fill the frame with gravel, leaving 1" from the top. Again can rent a compactor when done, but we just wet with the hose and hand tamped. Gravel is $75 a cubic yard (aka a "scoop") from Denchfield, we needed about 10 yards. Again, Casa guy did alot of this. There are online calculators to help you figure out your area vs how much gravel you need. $750.
4. Fill the remaining one inch of frame with stone dust. Tamp the stone dust down, it compacts alot so we needed more than the calculator said. We got about 7.5 cu.yards total. Same price and place as gravel, ~$500. We "Screeded" the top of the stone dust to make it perfectly level with top of the wood. We may not have tamped down enough in a few spots because there are a few dead dribble spots.. We ended up putting the tiles down, realized we had several dips in the stone dust that led to dead dribble spots, picked up all the tiles and filled in any dips and put tiles down again. Still have 1 or 2 dead spots but it is 90% there. Wondering if I drop stone dust from the top of the tile/deadspot if it will sift through the tile holes and fill the deadspot. Then wet and agitate the tile to settle the dust. Haven't tried bc I ran out of dust.
5. Get the tiles. I know someone that has Versacourt tiles with a rubber pad over the stone dust which is nice, but the pad makes the ball dribble very softly. Versacourt is more expensive. We used this 24x20 kit, $1500: https://www.rubberflooringinc.com/int...
6. Get a hoop. A top of the line in ground hoop is $1500. Someone just gave us a free portable hoop that should last us a couple years before plunking down for a really nice one. A starter hoop is $400.

You can also do a cement base, which is the same cost and is a better surface for play, but worse for drainage of water so you may not want that close to the house. but you can add french drains to solve that problem too. For more info:
https://www.versacourt.com/subsurface...

and for further gravel instructions and a good image:
https://www.versacourt.com/cmss_files...
again, we did not do the rubber top pad shown here.