Try a large or giant size wire dog crate. They are really easy to set up. You may need to put something around the bottom edge to keep bedding and poops more contained, but that should be pretty easy. You can add a level if you want as well. I would recommend one at least 2X3ft, but bigger is good too. These can be a tad expensive, but you can find used ones that aren't as expensive. One advantage is that they are easy to fold down and move.
Another option is an x-pen. These are typically 8 panels that are 2ft wide. You would need a bottom for it. They can be big, but you can take it apart with a bit of work.
NIC cages are great as well, but to take some work to put it together. You can make it as big as you want and it can fit most spaces. It can be pretty affordable if you can find the grids at a good price. They are also easy to build up, so you can give a rabbit more space without using a ton of floor space.
Most pet store cages are too small for an adult rabbit, but there are some out there that are 2X4ft, so would be suitable for a rabbit. They can be a tad on the pricey side though.