I wouldnt hold your breath with that. No one would want to downgrade their equipment going from L lenses to entry level crappy lenses. If you had say a 24-70 or 70-200 2.8 IS and looking to replace those with other L lenses, then you might have a shot.
So unless someone has the lenses for sale, you might want to look at your local Craigslist and such for those used lenses.