I've been looking at these add-on speakers for months and they've finally dropped down to their lowest price in around a year.These are good if you already have a 5.1/7.1 setup, have an AVR that's ready for Dolby Atmos and won't be roof mounting anything. Prices in Australia are $300+ and they have pretty good reviews as well.
These usually sit between $180-$200USD on Amazon throughout the year.
Just a word of caution that you should only get them if your existing set up consists of Pioneer speakers. Otherwise, you risk having a tonal mismatch.