Definitely get an opinion from someone else that can see the car in person if you don't feel comfortable making the determination of whether it'* worth it. It'* pretty tough to judge by pictures, which is why I've never bought a car on ebay.
And what I meant by quality is the material. A lot of the reproduction parts use inferior material. For example bumpers and other metal parts often are made with slightly thinner steel.
Trim is definitely a big one though. That stuff can get ungodly expensive since a lot of it isn't reproduced unless you have a Chevelle or Camaro. If this car has all of it'* trim in good shape, you could probably get $500 out of that alone. I'm not familiar with Buick, but with Oldsmobile you can get a couple hundred bucks just for the headlight buckets, a couple hundred for a bumper in good shape, a hundred for a set of wheel well trim, etc...
2003 Black SLE-Stock
2000 Mercury Mountaineer
1968 Oldsmobile Cutlass Convertible-455 cubic inches of muscle