The size of the speaker system you have (or hope to expand to) will typically dictate the price point of the AV receiver that you consider, as brands will tend to decrease the number of channels with each step-down model. More expensive AVRs will have more power and be able to drive more speakers for larger Dolby Atmos and DTS:X set-ups or speakers in additional zones.
There is no hard and fast rule as to how much you should spend on each component in your surround sound system, but you’ll be doing your speakers a disservice if they cost 20 times the amount of your amplifier and vice versa. Usually, we’ll put a few pairing suggestions in our reviews, so that’s as good a place as any to get a broad idea of what will work, but as a rough rule of thumb, you should budget to spend around half as much on your amplifier as the cost of your speaker package.