Dealerships don't splice and weld. They replace. And if it is all rusted together, they replace it all. I an see where they are coming from. This is why you do not bring a 10 year old truck to a dealer. After 5 years and warranty expired, the dealer is out of the picture.
I was at a VW dealer 2 or 3 years ago waiting and they were quoting some poor bloke on the phone. New catalytic converter(s) on his Passat - $3.5 or something on that order.
G