Well then, you are looking for either an Elegoo or Creality. Those will fit your budget. But you will not find a 400mm printer for anywhere near your budget, (assuming you mean build plate size) for $1000.
Prusa XL (360x360x360 build) starts at $1500, but personally I would not buy in just yet without careful review. I’d give them time to mature the design.
Open source, huge fan base and stellar tech support is what Prusa has going for it. Their slicer is top notch too.