What's the best thing to use as ground cover for garden area/backyard?

Hi Marlene, crushed granite really is very expensive. They make mulch now out of recycled tires that lasts forever and comes in just about every color you can think of. I know it would be more affordable than granite. There's always the regular mulch option too but it would eventually deteriorate.

Hi Marlene you might also consider Pea Gravel I did try to compare prices but I don't know what region you are in

Price out the small, smooth river rock. The very smallest, like pea gravel size. Being a senior citizen myself, that is the easiest to walk on, except for sand. You could do white sand with weed barrier under it.