You want to buy an apogee par meter. Home depot doesn't sell them. You do not want a lux or foot candle meter. Lux or lumens has nothing to do with plant growth. Lux meter shows how bright a light is for human eyes. Par meters measure the amount of photons (umole/s). The sun at midday is 2000 umole/s on the surface of the ground. Your average 1000w hps is about 1500 umole/s at 12 inches away.
If your getting meter to find where your dark spots are in your room or to compare hoods or test bulbs for age a cheap meter off Amazon for $20 will work.