A durable front wheel can come in as light as 2 or 2.1 pounds. Rear wheels start around 2.4 and can easily get to 2.9.
A few general principles to note:
- rim weight is far more important that hub or total wheel weight
- tire and tube weight are as important as wheel weight
- lower weight and (especially) higher quality of a wheel and tire are usually the most cost effective bike upgrades you can buy
- the law of diminishing returns comes into effect quickly as you go up in price with any of the above components
All this is to say that if you have a cheap, heavy set of wheels, you can make a big improvement to your ride with moderate spending, by getting a set that is lighter, stronger, and/or smoother. Spending still more on premium wheel and tire upgrades will bring further improvement, but less so than the initial step up from cheapo to mid-grade.