You want to be careful, though... some plants need less mulch than others -- their roots need to breathe (or so I've been told by some master gardeners)
I lucked out this year -- neighbors were taking trees down, and utility companies were trimming branches away from power lines. The two truckloads of wood chips I've gotten from those places aren't as pretty as the mulch I buy from the suppliers, but I can't beat the price -- FREE.
When you consider that the first pile was 10x20x5, that was a huge cost-savings for me (I pay between $2-3 for a 2cu ft bag of mulch). The current pile was almost as big as the first one. I used it to mark out the beds between my trees. When it comes time to plant shrubs between the trees, I'll just move the wood chips away from where I want the shrub to go, and dig there. MUCH easier than tilling up an entire bed that then just gets mulched over.
I save store-bought mulch for the beds close to the house.
