if you want to be 'on a budget', any space you
already have can be used as an echo chamber. Just set it up with a speaker and mics to return. This can be a dedicated, specifically constructed space, but can also be your live room (presumably empty at mixdown time), the lobby, lounge, swimming pool, barn, garage or Batcave serving double duty.
the only real limitations are how noisy, or how sensitive, your neighbors are.
I personally prefer hard surfaces, tile, cement, (limestone?) etc. But a case can be made for a nice wood room
how about a stairwell?
or a hallway?
or a
bathroom?
.