Looking to buy a Passat

[anotheruser]

So I have a few questions.
I have a Fors Focus, Ghia, 56 plate, petrol, manual, 113,000 miles. It's in pretty good shape, although does have a small bump on the rear passenger side arch near the door. Full service history.

I also have a Ford Fiesta, 06 plate, diesel, 117,000 miles. Not great shape as needs a new gearbox but is a great car.

I'm looking at a black 2.0 TDI R-Line to be exact. The TDI is the engine type yes? What is R-Line?
It's a 59 plate, diesel, 81,000 miles.
They're looking for about £5800 - is that a fair price? I known it's hard to say.

I'm not sure if I can really afford it as the priority is to get rid of the Fiesta.

Should I look at a private seller?

Thanks for any tips.