Yup, that's about what I used my first led grow. 2 x Mars300 (135w each) picked a pair off eBay for $120 total. In a .8x.8m tent also. You could add another light in there on the high side. I ended up using ~450w at the wall of cheap leds in that sized tent to fill it up.
Should be ~75 cents/day at US average for ~350w total at 18/6, definitely pretty cheap to grow your own pot.
. At $1/day, $90 for a 3 month grow, maybe $100 in seed and supplies, I'd expect a minimum yield of 4-5OZ, pays for itself on the first grow. 
Should be ~75 cents/day at US average for ~350w total at 18/6, definitely pretty cheap to grow your own pot.

