Your speakers are rather young to have failed already. Are they buzzing?
I don't think a 2000 has air bags in the door panels, but if it does, disconnect your battery and be careful.
You are right to hesitate to go to the dealer. Replacement Harman 2.5" speakers are $110 at the dealer, and they are not great speakers.
Visit the Car Audio/ICE forum. There used to be a sponsoring member there who sells audio equipment and will tell you everything you need to know whether you buy from him or not.
You might find the repair job I did on one of my e36s interesting. It is on my web page:
Speaker_Repair