Scrap, sell, or drive into the ground? NCT failed..

Hi all. I'm finding it hard to get a straight answer off a mechanic with my query, so wouldn't mind a second opinion here if possible.
Failed my NCT a few weeks ago, and brought car for a routine service as it was due one.
NCT failed on what was labelled an oil leak in the engine, so it failed on that and the emissions.
Went to the mechanic, and turns out I have two injectors that need to be replaced.
It's an 05 Astra diesel, so my thoughts are it might cost way more than the car is worth.
To kill my curiosity, can anyone estimate how much I'd be talking for labour and a few new injectors? More than €500?
Mechanic finally mentioned calling in so it could be stripped down to get a look at it... I'm not going to that hassle...