My mother-in-law usually picks these sponges up at Walmart when they are needed. I think they cost between $3.00 and $4.00 for a three pack.
These sponges are really pretty nice. There is a softer yellow side for basic cleaning, and then when you turn the sponge over, you get the green side, which is more abrasive and heavy duty. We use these sponges for washing the dishes, cleaning countertops, stovetops, sinks, etc. The green, more abrasive side is great for scrubbing pots and pans. When the sponges wear out, we just purchase another three pack, which can last us a while depending on how much cleaning we may be doing.
There is a warning on the back of the package that the green scrubbing side is highly abrasive and should not be used on more delicate items, such as glassware, porcelain, plasticware, or anything with a polished, brushed or satin finish.
The sponges can be sterilized by boiling. They are also not for aquarium use, as they would be too abrasive on the glass.
I like these sponges for general cleaning and doing dishes. My mother-in-law got me started on these, I had not been using anything like this until she introduced me to them.