If you have the space, make a permanent flower chamber that is 3 x 6 feet, which is the correct size to run a pair of side-by-side hps400, and then do your vegging under something even as simple as a couple 4', 2x40w T12 tube cool white flouro shop lights which will run you a total of less than $30 at home depot. Keep the plants low and short, and less than 3" away from the light. If you run 24/0 in veg, you don't even need to worry much about creating a grow chamber for veg, since light leaks aren't an issue in constant light conditions.