M.A.
I used a "messenger" bag as a diaper/purse. I bought mine at Target, however, they sell them at Walmart, Office Depot, Staples, etc. The purpose of this bag is for carrying a laptop, files, notepads, etc. It has two basic compartments with LOTS of handy little pockets, nooks and crannies. You can choose from different materials. I chose a black cloth. As much as you set that thing down on dirty floors and dirty shopping carts, its nice to be able to toss it in the wash!! (I put mine in the dryer,too)
Good Luck in your search!!
Margaret :)
P.S. I paid about 25 bucks for mine. Its still going strong and I purchased it about a year and a half ago, and I've washed it 4 or 5 times.