Where/what To Buy - Obx Exhaust, Wideband, Narrowband

Hey guys,

I'm about to buy OBX exhaust, a new front O2 sensor, and a wideband O2 sensor for the rear (no kitty).  Just wanted to check in with the people who are smarter than me and see if they know of any better or cheaper things to get.  I know there's better exhaust, I just don't have the money for better exhaust.

Here's the wideband:

http://www.amazon.com/Innovate-Motorsports-3795-Complete-Wideband/dp/B001QFH2RW/ref=pd_sim_auto_7

OBX exhaust is the normal price ($350, plus shipping)

Here's the narrowband:

http://www.amazon.com/Bosch-15097-Oxygen-Sensor-Fitment/dp/B000BZI3G2

Soooo, thoughts?  Is there a better/other wideband you would suggest?  Is there a better place to get the Bosch O2 sensor? 

Thanks!