The way they used to do it is to put something like #225 in real weights, then fake the rest. The best were aluminum plates which ran about about #15 for a #45 sized plate. You get the clink of metal, and they have a little weight to them so you get a more of a realistic look from loaders, when they bang into things, etc.....
Also before they got popular, bumper plates were great for this. The old HBO show "1st and Ten" used to use bumpers a lot when setting up a big lift.