P.T. Barnum was right. "There's a sucker born every minute."
You can build the Linkwitz LX521 system for as little as $6000, and it will stand up against the $50,000+ systems all day. You could easily drop $100,000 and more and get sound not as good as the LX521. If you haven't got the courage to do the project yourself, there is a company that will sell you the full system, fully built and ready to run, at about $20,000.
This is a full system that includes amplification because it is multiamplified and uses an active crossover.
The LX521 is not hard to build. Madisound sells flat pack kits, and there's nothing to stop you from having a local cabinet maker do up a custom set for you at a reasonable price. Any competent cabinet maker could knock them out in a day or so.