Is there any disadvantage to buying used headers?

 

Already rusty? Missing hardware? Wont last as long?

Depends on the headers really. If they're coated or stainless, it might be a great deal. Even regular headers, if in decent shape, may be fine used.

 

These headers look like they have some surface rust. I will have to buy new hardware and gaskets if I get them. If they are starting to rust should i just pass them up?

 

Rust would deter me from buying them, but it's your choice. If it's just a little on the surface, they will still probably last for many years. Any headers you get that aren't coated or stainless will rust the first chance they get anyway.