How to get a Barge in SP:
Open the console
Type "base iw09_03_base"
Type "cash 1000000000"
Buy a Barge
Type "base Manhattan"
Undock, explode, try a different base.
PS: I find it amusing a lot of people use Cheat Engine (for educational purposes of course).
Combine them with FL_Stat and Freelancer Companion, and you get just about anything that's on a base in less then a minute. If you want to swap engines around and get ships that aren't normally assigned to bases, I'm afraid I haven't the faintest idea where to start.