I just accepted a new job in the corporate world and unfortunately have to abide by strict dress codes and such now. I'm used to wearing whatever I want, but now I'm being put in a dark blue button up shirt with khakis and they've left the shoes up to me. The only requirement is that they must be completely flat on the bottom. All the shoes I own contain a heel unless they're gym shoes, but I don't intend on wearing trashy gym shoes with my uniform. Any suggestions for comfortable, not too pricey shoes that would go with my uniform? Mens size 13 please.