I can't think of anything that is more satisfying in the garden than looking at a freshly mulched flower bed (primarily because a freshly weeded flower bed is a whole lot more work!). I know that the act of putting down mulch is going to save me a lot of weeding and watering later on, so the sore back and dirty fingernails are totally worth the work.
We learned quickly that buying bagged mulch is not a cost-effective option. We much prefer to buy our mulch in bulk, and haul it back to the tea room in our dump trailer. Black mulch is my favorite, because it looks best against the green tea room and my preferred flower color palate (bright, cool colors).
The most budget-friendly option that we've found in our area though, is the tree bark mulch that comes from the city yard waste recycling center in Springfield. It's not dyed (at least, the mulch that we have access to isn't) but it is less expensive than dyed mulch. If you have access to a pickup and trailer, this is the way to go.
People don't typically spray backyard trees with herbicides, so the risk of herbicide damage from the mulch is low. The only potential drawback that I know of is juglone. If the mulch would happen to contain a lot of black walnut, it could potentially harm sensitive plants such as tomatoes, peppers, peonies and roses.
Tree bark mulch isn't the be-all, end-all of mulch. In some areas, it might be the most expensive option. Maybe in your area, it's pine straw, or coconut hulls, or some other agricultural byproduct that is the most affordable option.
A bit of caution on mulch: Don't smother plants with it. A nice thick layer is great, but most plants and trees would prefer a little breathing room between the mulch and the stem or trunk.
What is your favorite type of mulch?