If you are not going to get a MH you could veg with HPS and supplement it with CFL.
I have vegged with cfl, hps and a T5.
The MH works best. Plants vegged under cfl and t5 tend to stretch.
There is nothing wrong with vegging with hps.
MH runs a lot hotter than hps. My 400 watt mh is hotter than my 600 watt hps.
My t5 has 12 bulbs and is 648 watts. It runs cooler than my 400 watt mh.
I am surprised no one has mentioned that with that much space, you should make a veg room inside your grow room.
Just make a box in the corner. I saw a room where there was a hole cut in the wall so you could access the veg room while the bud room lights are off. You could also get to it from inside the grow room.
I have a 3x3x6.5 tent and small veg room (now a seed crop room) under the stairs.
10x10 would be a little slice of heaven for me.