I have seen canopies hung from "lamp" hooks and chains... but you could use rope or cord
You could use chains or get a bed frame
Chains on hooks
Not a vaulted ceiling but I used a plastic crown thing for my granddaughters attic room in our house. This is just one of those hoop things. so much depends on the weight of the fabric you want to use, the style of your room, how much you want to spend, etc. etc. There are always answers but one is right depends on all those considerations. i.e. the one pictured here is over a folding bed, and the net itself was found at our town swap shop. So budget pretty close to zero.