Stylish ways to bring lunch to work?

I want to start bringing my own lunch to work to save money, but my messenger bag isn't big enough to fit bulky tupperware. I'd rather not wear a backpack to work if I can help it. I commute via bus/train. Any ideas how I can bring my lunch without killing my fashion vibe? I suppose budget would be $100-400 but ideally on the low end if it's really just a lunchbox or something. Thanks!