I have the 36x18x18 exo terra, and it is big enough for ONE dragon. It has the same dimentions as a 40 breeder. You do have to be creative with the lighting though so that the top doesn't melt. I have a 50 watt halogen spot light and a a few other incandescent of daylight CFLs around to very the lighting deal.
What you have right now, is WAY too small for your beardies. Go to walmart or wherever and grab two 60 quart sterilite plastic bins. They make excellent temporary housing, they are clear so they are almost like vivs and most importantly they will give your beardies the floor space and privacy that they need.