I don't agree with the advice to buy all from one brand.
In my opinion, to know what you must spend you must first know what you like as far as music is concerned. Are you listening to music ( by that I mean sitting and actually listening for hours?) or do you listen to music as back ground music while you are doing something else. It may not seem that this is important, but actually, it is.
If you want to try to reproduce stereophonic sound from concerts in your home, and have the artist step out of the speakers and set up their equipment and play in your room, then you are sitting in front of a right and left speaker. You can tell (if the recording is correctly done) where the artists are on stage, where the lead singer is standing, how wide and deep the stage is, etc.
If you are listening as back ground music doing something else, you won't hear this, nor will you care.
This distinction can help to determine how much money you should spend on equipment.
Same is true for quality of reproduction of musical instruments. I was a classical violinist, clarinet, sax, oboe, and other instruments. I know what musical instruments actually sound like. If I don't hear that from recordings or audio equipment, then I'm not "there" and I have to keep upgrading until I get "there". Otherwise, I can't sit and listen. It drives me out of the room if it doesn't sound right.
This also helps determine how much you might have to spend.
If you establish a budget first before knowing what sound you like, you will be upgrading till the cows come home. Know what sound you like first, then go research and listen to the equipment that gets you "there".
Then, establish a price point budget for the equipment.
Go listen to equipment in high end audio stores. bring the music that you really like with you.
Go to audio societies and club meetings and meet people and listen to their and your friend's equipment. Know what sound you want and like before you go shopping.
don't let anyone tell you what you like.
You are going to buy equipment, set it up, listen for awhile and realize that you aren't quite "there" yet. Then upgrade one piece at a time.
I can almost guarantee that you will not end up with equipment from the same manufacturer. But, you will end up with equipment and sound that suits you.
take your time, go research, go listen (extensively), listen for yourself and enjoy the ride.
enjoy
