I've got the ATLANTIS 780, and thoroughly recommend it. It does seem expensive for a plastic box. Seems like the price is pretty much fixed wherever you go. No one seems willing to discount.
I like the Thule because it's really easy to get on and off with the locking mechanism. You just put the box on and hand tighten the clamps. Only takes a few seconds. The Thule racks can also be key matched, so you only need one key for the racks and the pod. I really enjoy using it.
Previously I had a rhino, and it wasn't really as sturdy. One side of the dual side opening broke, and I couldn't get it fixed, because the supplier no longer keeps parts. Really noticed the difference in quality. Took me quite a while to get it on & off the roof. Wasn't too bad, but it was annoying at times, when I just wanted to take it off for a while. I ended up leaving it on for weeks after I came home, till I got round to taking it off.
I use my roof box to go to the snow a couple of times a year, and usually camping or other trips away with the family. Really handy. I wish I'd bought a Thule first time round.
Good luck
ps. if you're interested in my old rhinobox, (it only opens from one side now) send me a message. I'm in Sydney