For what you're doing, a dynamic is a good call--they'll eat the bounce off the walls. Don't worry about a tight pickup pattern so long as it is generally cardioid; with dynamic mics' general falloff, a wide cardioid pattern is not going to hurt you much. Consider the AT2005USB or ATR2100USB; both microphones are USB/XLR so later on you don't have to dump them if you want to get fancier and they sound very good for the price.

Feel free to e-mail me if you'd like to chat about this; I do a little bit of audio wizardry on the side (and I'm building an open-source podcast serving platform at the moment, as it happens, so I've spent time in the weeds--maybe it'd be a good option for your hosting).