I think some stuff like the motor mounts and and the fuel pump we can already get a decent price on. I don't know how you would get a group buy on a welded cage, unless you gonna get someone to take all the measurements and then provide the materials, and you get someone local to weld it in? And from what I've heard bolt ins are pretty useless besides looking cool.
However the carbon fiber and the rear diffs I think would be great, as we have limited options for those as it is, let alone at a good price!