Tread very very very carefully my friend. You are getting sucked into a "hobby" that will haunt you forever. You also get a life long disease. UPGRADE-ITIS. There will always be a "weak link" to fix, better quality to chase, more sound stage to be discovered. It is never ending. Quit now, never come back and be happy with what you have.
But, since you will not listen to us adults

...
I second the suggestion to put all your money towads a sub. DIY like a package from Dayton will give you best bang for buck. Also look into Bic America, their subs have good reviews here. Later get the fronts speakers with an entry level reciver.