Actually the bases could (and have been) made fairly inexpensive.
GW (Games Workshop) made bases just like the ones that you have for their Titans. They were 2 piece (molded) and you cut out a small dial, place the dial on the bottom piece then snap the top piece on.
There are also bases out there for planes/spaceships that have a spot for a small d6.
GW I do not think would go after you unless you made it just like theirs.
Now you could make a base that had a small spin dial that just sat on top of the base. I have seen (can't remember which game right now) a base that you actually places a cut out on the base that showed directions and other information about the ship on the base.
If you decide that you want to do bases, check around with some of the different manufacturers, (like China, HK and Singapore) because they might have something that will work that they have already made for another company that was rejected.
Dave