I am sure the most annoying thing about breaking a lava lamp is the clean-up. If you must experiment, break it over a large thick garbage bag. I think the flubber is not as thick as you think it is.
Mathmos make the classic retro tube shaped lava lamps and have a website (www.mathmos.com or www.mathmos.co.uk). There are lots of online suppliers if you put 'lava lamps' into Yahoo or Google, and eBay have quite a few of the classic rather than roc...
I've had my lava lamp for over 30 years. I've had to occasionally change the light bulb in it. Does yours need a stronger bulb?