Audio Systems: Installing speakers, quality speaker, woofers

Question
I don't really speak english but I hope you understand. In the past week, I am getting a rattling of my woofer????? ( the big one on the backside). This has never happened before. Does this sound like the speaker is blown? If yes, do I have to replace it with the lexus $525 speaker plus installation? I want to keep the integrity of the system. My friend says we can put most any quality speaker in that matches the ohms.Is that true too?, and can you tell me what kind of speaker i have to buy and how to install it. Any help or suggestions would be helpful.

Answer
original speaker is to expensive, you  need a speaker that is 1.5 ohms or 2.0 ohms max
the speaker also needs to be freeair

kicker
jl audio
kenwood
pioneer

i am sure that there are 2 or 3 more brands that have freeair speaker

all the othe woofers needa a box to work

good luck