I understand it's alluring to see amplifiers for under $100 that claim to deliver "2400 watts!" or subs that claim to handle "1800 watts of power!" for $40 each for a 15" sub, but ya just need to stop and think to yourself, "Is this too good to be true?" Yes. It is. The products don't perform as advertised, and are poorly made at that price. This isn't a cheap hobby. It never has been, and believe it or not, it's actually gotten better and more affordable over the years, but it's still not cheap to get into and do it right. That being said, don't be afraid to save up and buy parts one at a time till the system is complete. In the end, you'll be much better off, and beating most of the people who couldn't wait, so they ran out to Best Buy and got a "fast and furious" audio package.
None of my systems were done overnight, but I've never had a complaint once they were finally complete.