we just went thru this w/ the 05 we bought. there are a couple places in canada that have them and on google we found a zillion of them. we didn't find any defenders in the states that we considered to be reasonably priced relative to the condition they were offered in... ours ended up coming from stuart foley in england and was an all world spec lhd 05 w/ 2500 miles from new for about $30 ,000 USD. the shipping to the carribean was another couple thousand but when i was looking at getting it to and thru miami , it was about the same.
i didn't see any stateside that were either not complete beaters or wildly overpriced for what they were.
if you have not imported street vehicles into the states that were not specifically DOT approved, i would simply suggest that you research that very very throughly before you try. there were some exemptions for older vehicles and trucks but they were changing those rules about once a week and it is very easy to get caught out. also when people were just driving them across the border from canada they would end up at their local DMV with a VIN # that would bounce in the computers as non-us spec... and that was the end of that. its all doable. just be prepared for a lot of paperwork and a fair amount of time w/ US customs and then the DMV.