The cheapest but riskiest way is Ebay or Craigslist for a used replacement. We had to go that route with our 325i. It worked for us.
Pick the biggest city
near you so they know that you know where they live if they stiff you.
Or if you can mortgage your house you might find a responsible mechanic for rebuild.
Heck, George W Bush is handing out money, ask him!
