I just rebuilt my engine and had to handle the metal trans cooler lines probably like yours (no info on your M-B year or model). The lines are a soft metal and bend fairly easy - I would think that brazing would be a suitable repair and permanent (perhaps even really good epoxy) with a very good cleaning of the line to remove all grime and ATF before brazing. Or, a local junkyard would have them. I'd bet M-B would want at least $150 for the line if not two or three times more. I replaced the grommets (mine were like hard plastic and broke into pieces when handled) and the new ones were soft and pliable. M-B had them for $1.22 each, but had to order them from a regional location (Dallas).

Good Luck!
Tom

__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.