Depending on your gameplay, you may not need much iridium.
I usually use only the crystalarium from the community center bundle, for jade for skull cavern stairs. I think at most I had 4, doing jade for stairs, diamonds for Jodi and Marnie, and amethyst for Abigail Clint Emily and the dwarf. I just have never played that way, although I might sometime. I don't really minmax. I minmin, hahaha!
I always use iridium for the wizard's mail request, to upgrade my pickaxe and axe, and craft the iridium band.
Sometimes sprinklers but usually I buy from Krobus. Sometimes the warp totem recipe, but I usually just take the bus.
You can sew a shirt with an ore and breastplate with a bar. The ore is excellent slingshot ammo. You need bars for obelisks, and bars are loved gifts for Clint Maru Krobus & Willy.
And Willy asks for 5 bars.
To complete perfection you'd need enough iridium for a slime incubator, hopper, etc.