Is $3,000 to replace all original house breakers a fair price?

My AC started short cycling, and the AC technician said the breaker is 50 amp while the AC is compatible with a 30 amp, suggesting it would be a good idea to change it. I called an electrician, who came out and said all my breakers need to be replaced because they are the original ones installed when the house was built in 2000. I'm wondering what my next move should be, specifically if I should get another quote. I'm also concerned about the bonding bar the electrician said I needed, as he told my wife that without it, it could kill someone, and that 'the blue needs to be all connected'.