Hmmm,
Have you thought about blowing up your model using pyrotechnics?
They are relatively cheap but you would need to have someone who knew what they were doing to get the right effect and to be safe also.
But this is another option you could look in to perhaps.
I have fired pyrotechnics on a couple of occasions... But the law is a lot more strict now with things of this nature but they are not that complicated but I would advise you to speak to local Lighting Stage supplier could help you on this but money is the problem with this stuff I understand.
Try this dude