We do a number of graduation related productions from grad nights to parties, to ceremonies to asssemblies. I all our dealings with our high school, even middle-school clients, part of our production compliance calls for access to either a comped copy, or a loaner. Often we get a copy that was not "sellable" due to imperfections, but that meets our graphics requirements with no problem.
On the occasion that we simply cannot get ahold of a current copy of the actual school's yearbook publication, we have often found usable yearbook prop/graphic materials are our local public, or school libraries, available for loan.
Lastly, do a Google search for yearbook publishing companies in your area. Many of these have scads of old, out-dated, damaged or returned products sitting around their storage areas. You could get lucky and find for free exactly what you are looking for, representative of a printed publication for your video yearbook.