Veg Tent Question!!!

I know this question has been played out but from what I have read on forums still have not clear up making my choice, So I apologize in advanced.

Trying to think about a veg tent set up for my next harvest. Planning on a 3"x4" tent. I plan on growing 4 plants hydro in a veg tent and flowering tent. I'm struggling with the light to chose. I know hps and MH would be better for veg but I'm looking for a more cost effective veg tent. My flowering tent will have a 600w hps just for your information. I have looked into t5 and cfl, and just don't know which will be better for the 2-2.5ft tall vegged plants I am going for. I have read from many forums here that each has its drawbacks, and was just wondering if some would help me understand what light to choose with the size and set up I am got in mind.

thanks

Cost to run or cost to buy? A 400 MH is going to cost about the same as a good 4 ft 4 bulb t5. The t5 are only about 200W and will be cheaper to run. Less heat so less cooling. I would go with t5 but, that's what I use so I am not without bias. Good luck with whatever you land on!

Thanks that helps a lot, yeah I'm more concern with cost to run.