Cost is directly proportional to bass response and loudness needs. So figure out those requirements first.
Listen to music with a sound level meter. Figure out what your realistic SPL needs are at your listening position.
Then, given that preferences for sound are highly weighted towards bass, make a decision about your subwoofer placement options.
Then find a system of subwoofers AND speakers that meets your needs. And, if you are willing to cross your subs higher than 80 Hz, you can get great sound for less money because you won't need your monitors to play as much bass. Just for perspective, the Genelec 8030 play as loudly as the KEF LS50 Meta and they come with amps. Don't be afraid to use "small" speakers if they meet your needs.
Having said this people will tell you it needs to be louder or that you can't cross over above 80 Hz. But if you read through these forums you will find that neither is absolute truth. It is really what you prefer that matters. And if you make a mistake, you can always upgrade your monitors. You probably won't need to upgrade your subs. Which means the final recommendation is to buy monitors that you can resell relatively easily.
It is an experiment to some degree, but that should be part of the fun and challenge.