> the supply potential of indium at a minimum of 1,300 t/yr from sulfidic zinc ores and 20 t/yr from sulfidic copper ores.
(ie potential max supply estimate as by product from mining other minerals)
This is almost double the current demand. Other industry reports are more optimistic than the source cited here in wikipedia but as a ballpark it'll do.
The wikipedia article has a decent description of one facet of the rare earth problem, that these elements are always bound up with other elements and are only economically feasible as by products.
The other great issue is the flip side of the same issue; they are bound to other elements and must be chemically seperated after mechanical pre processing .. and this can be lengthy, expensive, and leave acres of toxic waste to deal with.