I don't know, Cheryl. For me, the dyed mulches are simply an aesthetic choice. I cannot imagine that the dye makes one bit of difference. I guess "rubber mulch" lasts pretty much forever, but personally, I don't want rubber surrounding my house.
I guess, since rubber mulch does last so long, you would soon make up for the expense. It is very expensive and I have only seen it by the bag.
I want natural, un-dyed mulch. No other reason than I just like the aesthetics of it.