If the blade he is selling are OEM blades then the quality will be equal, if
he is selling a jobber blade then I would say no. All the jobber blade I
seen are lower in price for a reason.

most of the tractor blades Sears offer are one quality style that came with
it when new and a premium blade, usualy the premium blade is a few $ more
and suppose to last longer, however the abuse the blades take that I see in
my neck of the woods make the life of either blade basically the same.