Gen 3 3sgte Oxygen sensor replacement options?

Hi all,
 
I'd like to replace the oxygen sensor on my gen 3 (4 wire) and am wondering what options there are to do this? (Gen 2 USDM 4 wire sensor has a different plug btw)
It seems as though Denso does not make a direct replacement (Quality aftermarket unit) and I think Toyota would absolutely rape me price wise for a genuine one.
I think I read somewhere that a 1994 4Runner O2 sensor has the same electrical plug and mounting base but just a tad longer in the wires.
 
The ecu is not reporting my current one to be faulty but I know the car has been running extremely rich prior to me buying it and resolving the engine issues. I figure the current one is not operating like it should as its probably covered caked on soot etc. I'd like a new one just so that the engine will be runing at its prime and with the best possible fuel efficiency.
 
What have you guys done with swapping out the Gen 3 Oxy sensor?
 
Cheers,

The engine definately runs fine without it but as i'm in the process of replacing/adjusting/calibrating the various sensors, cables and whatnot, it is the last item which I cannot test to confirm it is actually working properly. Normally I wouldn't give a **** about an oxygen sensor but seeing as with this car I'm looking to have a standard(ish) reliable fuel efficient engine I'm keen on seeing what change a new sensor will provide. 
 
 

just_ace

by all means buy and fit a new one, but in my experience (i don't even have an O2 sensor connected/fitted) it makes no difference to the running of the engine. and i still get 10k/L

I have a 4 wire relative low usage 6,000 kms was bought new .
 
I have changed to a wide band as i have an aftermarket ECU

Totally depends on your tune. I can disable mine via the FC & I'll get 50km less mileage off a tank.

$130?