Good inexpensive light meter? Intensity/time?

[chopster01]

I searched "light meter" on this forum but didn't come up with any real suggestions. Is there a decent light meter out there that won't send me to the poorhouse? Currently I'm using a handheld photographer's meter and converting f-stops to footcandles according to a chart found in the book "Understanding Orchids" and all over the web. But I'm a little suspicious of my findings.

Also, if I get a reading of, say, 1500 fc under lights, does the light value increase the longer the lights are on: say 1500@12 hrs, 2000@14 hrs., 2500@16hrs.? Something like that? If so, what's the real formula?