[kamesama980]

Keep in mind it's not just the sensor, it's the controller too. Widebands don't output a voltage like narrowbands, they need a set of circuits to provide some voltage and current and that knows how to read the responses of the sensor. Part of the controller is also converting it into a signal for your ECU...the controller is actually the expensive part, replacement sensors for a wideband setup are in the $50-75 range.

What sort of ECU are you using? modified stock or aftermarket? that will also affect your options.

nitty gritty from memory of class last semester:
there are 2 types of wideband sensors, Critical Current and Ion Pump. critical current is a 4 wire (2 sensor 2 heater) and varies about .2V but the voltage isn't what's read. the ECU runs bias voltages on both lines to end up at 0V at the sensor at stoich. when the mixture goes off stoich, the voltage changes very little but what the ECU measures is the mA of current flowing and which direction to determine rich/lean and how much. These are actually made of Zirconia Dioxide like most narrowbands but they're physically different in the sensor. Exact voltages and mA readings will vary by sensor and car they're in.
Ion pump is a 5 or 7 wire (2 heater, 3 sensor, 2 trimming resister (may be in the plug or even the ECU itself)) and most expensive but also more precise. It's a completely different design. Again, you have bias voltages and mA is measurd to determine mixture but it's flip-flopped from critical current.

Either way it's not a simple circuit you're talking about building, unless you have oodles of time and like to figure out how to do things then troubleshoot and tweak for ages I'd just get the aftermarket wideband from race shops. you can get them for under 150 w/ gauge on ebay. That will be the sensor, controller (that can output a variety of signals for your ECU) and gauge.