compared to the damage moisture can do to a structure, i personally found it reasonable. but, mine doesn't run that much.
i've talked to guys that are using some of the high output lighting and paying 160 per month per light. power varies in cost depending on area considerably.
my 1200gal per day RO system cost a bunch to run. everything is a tradeoff. the guys in my area that are dropping 10k at a time at the hydroponics stores are all raising pot. i know of no other crop in CA that will pay for the heating, lighting, pumps, RO, dehumidifiers, chemicals, fish food, etc. (no i don't raise pot) certainly $3 per pound talapia and a couple of heads of lettuce doesn't. and i didn't even mention the number of hours of labor involved. i do it to have better veggies and the challenge of something new. my $10 a piece tomatoes (oh and the rats ate most of veggies including tomatos while i was away on an emergency) are kinda the laughing stock of my family and friends. but i get a lot of satisfaction raising living things.

Enjoy the wonder of God's creation.