I've been looking at stainless steel brake lines for my G35 and Amazon has StopTech parts available. They rear line are only $23 while the fronts are almost $90. Yeah, the fronts look (??) longer, maybe even 2x the length, but that doesn't explain an over 3x price difference. Why the difference ? One thing could be demand, as in the fronts are more popular (supply and demand) but do people only do the fronts and not the rears ?