How much should it cost?

I have had permanent retainers behind my upper and lower teeth for 10 years since getting my braces off. The bonding on the lower one has finally cracked, but only the middle one, so the retainer is still secured in place on either side. My dentist told me it’ll cost 150$ to literally get one dot of bonding put back on. I don’t have insurance, so I was just wondering if that’s the normal cost? The retainer isn’t damaged whatsoever, and the bonding actually got cracked by the hygienist at my last cleaning. Anyways just wondering if that’s the normal price, I’m only seeing stuff online about replacing the entire retainer.