Before investing in a light meter, do you have a SLR camera, by any chance? If so, you can use it's meter:
Light Intensity Measurement
An editorial comment: I have been growing orchids for over 35 years, and other than experimenting a time or two with the camera, I have never used a light meter (which is pretty amazing if you consider that I'm an engineer). I tend to be conservative when I move or acquire a plant, starting shady and moving brighter as the plant will allow if it's totally new, adjusting as it "tells' me. If I already am successful with that type of plant, and I know this one isn't somehow unique in that regard, I just plop it next to it's "brothers and sisters".