i agree with everyone if you are asking who makes monitor cages you didn't even research them that well. A Min of 4 long by 2 ft deep by 6 feet tall is the smallest you can go for a pair. Monitors are not a cheap, forgetful animal. They eat a lot. My rough neck(also an arboreal monitor) was in a cage i made that was 4 ft long by 4 feet wide by 7 feet tall. And man can monitors eat he would get 3-6 hopper/weaned mice a day($.35 x 4 mice(avg)=$1.40 X 7 days=$9.80 a week at least). the cage cost me at least $750 to build and get fully set up. One thing none mentioned is these are going to be display animals for you? I can tell you from personal experience arboreal monitors are not that fun to handle, they will climb all over you(if they are not scared) and will rip up your arms legs and clothing up, they have some sharp nails. think twice then think a third time if you really want to get into monitors they are messy like your cleaning the cage everyday, and changing water everyday. do some more research, check out P.E.'s monitors FAQ page some really good into in there.
Tom