Actually, when looking at correct lighting in photography, the actualy lightboxquality isn't nearly as important as the quality of the lightsource.
A lightbox tent really isn't anything more then a white cloth around your models to diffuse the light. It can be done just as well by certain types of paper. Investing in a good lightsource (preferably one with high Watt output) is much more vital to take good pictures.
Lots of light means low possible ISO settings for your camera. The lower your ISO value, the better quality the picture will be (it'll make it less grainy). It doesn't even matter what type of camera you use. ANY CAMERA will make a great shot when there is a lot of light present. Great cameras will take good shot at low light conditions.
So my advice for people struggling with their pictures: if you are going to invest in something, invest in high Watt output lights. Even if that means getting these contruction site flood lights (wich often rather cheap for their power and quite robust too). Something like this: http://www.benl.ebay.be/itm/New-Mex-...item1e5fe26cb4
Combined with this:
Doesn't cost a lot, will light up ANYTHING and is cheap as chips. The lamps do get hot over time however, so I wouldn't use them for shoots lasting more then half an hour.