For my Grandkids:
Sony Core CS-3 on sale for $98 each on sale
Sony Core CS-8 Center Channel for $79 on sale
Paired with an old STR-DN1070
Less that $300 all in.
A Sony STR-DH550 goes for $250 and 5.2 capable. You can have a decent 3.0 setup for less than $600.
The Cores go on sale 3 or 4 times a year.
Sony 75X900e/Sony STR-DN-1080, CS-3/CS-8/CS5
Sony X800 4K blu-ray player/Dish Hopper3
Roku 4 Premier/Sony PS-4