100 watt hps

i have a 100 watt hps light with a built in ballast. will this be enough for me to grow two plants and not spike the electric bill?

yes. id go 150 or 250.

not really enough for 2 plants unless theyre autoflowering or 12/12 from seed

You have to think of it like this,

Most incandescent light bulbs are 100 watts,

If you added a new table lamp to your place would you still be worried about spiking the electric ?

You'd probably need 4 - 5 1000 watt HPS running before I'd even begin to start worrying.

You'd have to keep the plants really tiny, I'd add more light if you want to grow enough for a serious smoker.

There's a posting on here listing where you can get a 150w complete HPS ballast/fixture/bulb for $20, add that with yours and you'd be able to keep yourself supplied indefinately.

Better to grow something than nothing though, so if that's all you got, sure, it'll get you started.

could i use cfl's in combination with the hps? i also have three 24' cfl tubes.

Yes, then use them all then.