I got a light meter for $30 from Cal-West orchids: http://www.orchid-supplies.com/misc_...ies.html#meter.

It's very useful for quantifying light levels, but before you spring for one, consider Kev's very good point. At what time will you measure the light level? If you have a catt that wants 3,000 foot candles, but your window's narrow and the sun only hits the plant at that intensity for an hour, what does that mean? If you have less bright sun, all day long, are you better off?

We don't need simple intensity - that's like voltage in electrical work, it can change over time. We need to know wattage. Watt total volume of foot candles (ie, avg foot candles over a specified number of hours) do these beasties need each day. Only then do light meters help us choose ideal locations.
Julie