I had a similar problem but had a replacement driver that I picked up on ebay a while back. My advice would be to:
1) look for a replacement driver on ebay around $200 - $250 when they become available
2) sell the unit as a parts unit with open driver (probably around $75 - $100 on ebay - I think the last one I saw went for $80 a few months ago)
Unfortunately you can not have the sub reconed - so you're stuck with the options above...
If you still have the unit I'd be interested in it as I like to keep replacement parts handy in case mine blows again - don't want to pay what Sunfire charges.