I actually once bought the Ba'ul Sentry Ship off the Exchange, which was awesome on the outset, until I realized that, once activated, I couldn't deactivate it so that I could start moving around again and set up for my next sentry start point after a battle had moved on. It's apparently a known bug that they never fixed. There are several workaround hacks that some folks have had luck with, but I've never been able to get it to work. I suppose I could always put the Teleport universal console on it and jump around, like I do with the Cnidarian, but I think I would kind of like to have something that just works the way it should, especially after an extremely high-energy battle takes out all of my sentries and I can't reset or get them back.