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highly recommended for the cabinet! like what most would have mentioned in other similar threads, you've already spent quite a lot for your gears, what's spending a bit to protect and needless to worry if they'll get fungus etc on them.
i got mine at carrefour, you might wanna check out other places that sells them too. and, no they don't eat too much electricity. so no worries about that too. cheers, and shoot more!
hmm i'm new to this slr world too but after reading all these threads i've decided to invest in a dry cabi, its not exactly very expensive as compared to the investment u put in your camera, take it as an insurance for your camera.