It might be easiest to order it online and have it shipped. Failing that, I would take the lamp to a UPS Store or Fed EX store and have it professionally packed.
I say forgetaboutit! Besides a lot of bubble rap and other padding it would be a good idea to enclose the lava lamp in a leakproof container. The liquid in a lava lamp has toxic fumes (similar to break cleaner) and is also very combustable.