Yes, you can move a tank and its inhabitants. It's not easy and takes a lot of pre-planning. Transfer the fish and coral like you were buying them from a store. If it's over a long distance you want to use a cooler or something to maintain their temperature. Save some of the old water from the tank to mix with your new water.
I have moved my tank in my house before and I removed everything into heated buckets with power heads - tore down the tank completely - moved it - rebuild it (added new substrate) refilled it and restocked it. The whole deal took a couple of days with my fish in buckets on the floor. The new substrate created a massive cloud which delayed my process, if you are careful you may not have to wait. I reintroduced everything with drip acclimation like it was new to the tank.
I would not put the water that held the fish back in the tank because the water my be nasty. I even did water changes in the bucket, because I was afraid that the extra boob from being nervous wasn't being broken down because there was not enough bacteria in the water to break it down.
It really depends on how far you need to move it and how long the fish will be out of the tank.
Look at some threads on this site and reef central for more ideas on how to do this. Plan, plan and plan some more - BUT it can be done.
If it is an out of state seller, then I wouldn't know who you would do this and control the process.
