This is my camera bag. When I need to carry my camera, or my camera and some other gear, from one place to another, this is often what I use. It's manufactured for Trader Joe's, to their specifications, and it works wonderfully.
As you can see, it easily has enough space for my Nikon D3100 and the Micro-Nikkor 60mm lens, with plenty of room left over for filters, cables, speedlites, and so on. Sometimes, I even put a sandwich in there:
You can see that I also use the GreySlow NoStrap strap product thing. My father used it, so I use it.
The bag is a little light on the padding, but so far, so good. Not being a professional, well, if the camera breaks it's not the end of the world. Mainly I try to avoid smashing the bag in to stuff, and so far it's working pretty well for me.
Here's the bag in use:
Note the ShurGrip(tm) cloth handles. That's my patented grip, though. You have to pay me if you want to hold your bag that way.
Note: I actually do carry my cameras around in this sort of bag. Have for years.