I bought the red 41" wide box from harbor freight a few months ago and I was waiting a while to buy the bottom, BUT, I scored a huge deal on a bottom box at work (home depot - where I work one day a week - they pay half my tuition).
The box lists for $600 and its all ball bearing. 42" wide and plenty-o space. Bought it for $300 still wrapped in factory packaging with no dents anywhere. I cant wait to get it out of the car and start loading it up