Ejection seats costs between $200,000-300,000. Most ejection seats weigh about half a ton and are complex bits of technology. There's a lot that can go wrong but rarely do you have accidents, and those are usually because of poor maintenance. Ejection seats became essential as military aircraft became so fast that a pilot could not safely climb out of the cockpit and jump. With the higher speed, there was the danger of hitting the tail. Also, escaping pilots were often injured or stunned and unable to get out quickly enough.
The first ejection seat design was developed in Germany, where the seats were first installed in their He 219 night fighters, in 1943. These used compressed air to propel the seat out of the aircraft. A year later rocket propelled seats were installed in the He-162 jet fighter. By the end of the war, all of Germany's jets were equipped with rocket propelled ejection seats. While the Swedish firm SAAB had also developed a rocket propelled ejection seat, it was British firm Martin-Baker that jumped in after World War II and created a design that quickly filled the needs of most Western air forces, including the RAF (British Royal Air Force).
The U.S. Air Force long insisted on using only American made ejection systems but the U.S. Navy stayed with Martin-Baker because the American ejection seat did not function as well at very low altitudes (where a lot of naval aviators have to eject during carrier operations). Martin-Baker supplies about two-thirds of the ejection seats for Western fighter aircraft. The other major supplier of ejection seats was the Soviet Union. Those Soviet era manufacturers continue to produce good ejection seats for Russian aircraft and some foreign customers. China is becoming a major player in this area, usually exporting Chinese made ejection seats in Chinese made aircraft. The Czech Republic and Romania also manufacture lower end ejection seats. Western manufacturers produce about a thousand seats a year, while Russia and China produce less than half as many, almost all of those seats are for locally made aircraft.
Over 10,000 aircrew have successfully used ejection seats since World War II. Very few have died in ejection seat related accidents.