Front Oxygen Sensors on 98 V6

I got a lovely "Check Engine" light over the weekend, but fortunately found out it was only an oxygen sensor problem (and not a cracked exhaust manifold). Unfortunately, I also needed to get my front brakes replaced, so I held off on replacing the O2 sensor to save some money. Does anyone have a recommendation on where to pick up some new front Oxygen sensors? I'm on a college student budget and can get my buddy to install them, but I was hoping to find a better deal than what my mechanic quoted me.