Jeez,
That is an absurd price Redboy.
Your mechanic has taken you for a ride, man.
Those heater pipes are perfectly repairable. If you get them out (have to drop the fuel tank) you can get it braised for $20 or something if you go to a radiator specialist.
 
This is a fairly well-known issue. I'm just sorry your mechanic did that so quickly without considering alternatives...
 
If I'd seen this post before I would've offered to drive over from SA, bring all the tools necessary and do it for you for half that amount myself.