Cheap Speaker "Isolation" Solution for 300 lb. Speaker

 Good Afternoon All,

I am looking for advice on a cheap and simple isolation solution for large, heavy (325 lb. each) floorstanding speakers. 

I've read much advice on granite or marble slabs, multiple layers of cork, springs, etc; while this has been helpful, it is neither a cheap or simple solution. 

Ultimately, I am looking to protect my wood floor from damage these very heavy speakers might do, as well as decouple the speaker from the floor in order to reduce bass resonance (I am in an apartment complex and worry about noise complaints). I've looked into sorbothane pads, but they never seem to be able to hold this much weight.

Thanks!