Looking for another vehicle

So over on r/jetta I posted a sad picture of my car which is probably a goner. I'm looking for a used vehicle & I'd like to stay in the VW family - I'm fine with the Audi or VW mark, however. My key question is, what can I expect if I'm looking inbetween $5k-$8k & am I able to negotiation prices?

Right now, I'm eyeing a really nice '06 Passat for $7k. I think I may be able to talk them down. I"m curious as to why the previous seller got rid of the vehicle however, given it only has ~40k miles. The only thing I see on CarComplaints is an issue with engine compartment fires due to COP & an investigation was done. I seem some other TSBs out there & complaints about cam wear -- but is that an issue on these models?

I'd be open to advice and/or suggestions & things I should look out for.