Rota comes to mind as combining (relatively) low cost + light weight.
For the most part, though, you'll probably find the combination of light weight + 'cheap' (and not in the good way...) in the lower price ranges. Why? Because there are really only 2 ways to get light weight in a wheel:
(a) skimp on construction and make it thin ('cheap')
(b) use more sophisticated materials and procedures to create a robust yet lighter-weight rim (usually not inexpensive)