The summon celestial in my version of the game doesn't consume the component, and a one-time cost of 500gp typically isn't a problem for 9th+ level characters in my games. The 40 hp is awesome, because it implies the celestial can do something more useful than simple DPR, i.e. tank damage that someone in the party would otherwise take. It can control its space and deal opportunity attacks. It can be buffed, which is especially great with auras. It deals melee or ranged radiant damage every round for an hour at no action economy cost at all, and can also grant temp hp and heal. Note that it takes an action to cast, but then the celestial takes its turn right after yours and can immediately take its two attacks per round. It can also be upcast, but it actually scales well: for example, when I cast it at 6th level, it gets three attacks per round.