I don't think there are any cheap ones of those and we're still working on support for them to start with.
Also keep in mind that there are at least two kinds here, AC and DC powered, so make sure that you get the right kind so it works with whatever motor(s) you're going to connect it to.
The companies I know of that makes these things are Fibaro (support is coming, not cheap), Philio (we'll most likely be supporting this one too), TKB Control (similar to Philio), Qubino (new Z-Wave guys, not cheap, but very small and looks like quality stuff) and Vision (DC only, not sure about support as yet).
There's also a company called MotionCo, but they do the whole things, although they're going to launch a motor only unit with integrated Z-Wave.
None of these are going to be cheap though
I don't think we've implemented support for light sensors in the rules as yet, but it should be there in the future.