I have ran O2s for years. First with narrow bands and then with the wide bands. In my opinion, this is a subject that is hard to be only a little bit pregnant in. The varying amount of alcohol affects the reading, you have to really know the carb's circuits in order to know how to make the necessary changes, you need the right carb that has all the changeable bleeds and jets or have a good set of tiny drill bits and taps and all the bleeds and jets to go with those tools. It can be expensive and exhausting to start.

You didn't say whether you were tuning primarily for track or street. They are typically 2 different tunes. The cruise and WOT settings are usually not real hard if the carb is the right one for the job to begin with. The closer the carb is to being right for the application, then the less mods will be necessary to bring it in.

The idle, just off idle, and transitions before the main circuits come in are the real challenges to tune. This includes the emulsions. They overlap so much and there are not a lot of carbs that have screw in bleeds and such in those circuits. Now those circuits are usually not as important on a track car. Pump shot alone can cover up a lot of ills in that area when the throttle only goes from fast idle to WOT. But on the street, those circuits are absolutely critical. Some cars even end up cruising on the idle and transition circuits. That is a real can of worms to sort out and means that major compromises must be made.

Obviously, I don't have any advice on a cheap wide band. I just thought it was important to touch on a few of the issues surrounding using one.