I'm not really a bag girl, I'm a shove-everything-in-my-back-pocket-girl. I'm just not very fond of lugging a purse. I'm even less fond of toting around a bag covered in cartoon characters in the name of diapers. When I got pregnant, rather than spending several hundred dollars to get a diaper bag I could actually enjoy hauling, I came up with the anti-diaper bag.
I simply took a toiletry organizer my sister was throwing out & went to town filling it with the essentials. It holds extra food, pacis, diapers, crayons, handi-wipes, napkins, all of the essentials. If you don't have a toiletry organizer you could use Ziplocs, the bags that wrap onesies & blankets (save these, they're great for organizing), or any other small zippered bag. Look at whatever you have on hand.
The best part is that it ties up neatly & can easily be removed for date night. Additionally, once you're past the diaper bag phase of life you'll still have a purse you can use, rather than something that screams, "I've held spit up rags & poop filled diapers!" Definitely a green, fashionable, frugal solution.