The average cost for a BR710 or a Tay engine from Rolls Royce is about 1.8 million dollars. I found that out during a tour that I took of the Rolls Royce plant in Indianapolis that manufactures those two engines which serve business jets (including Gulfstreams, Global Express, Challenger, Citations including the CitationX) as well as the ERJ135-ERJ145 family. Rolls Royce usually tends to be the most expensive of the big 3 engine manufactures, but arguable has the most reliable product that always will meet specifications, or there will be big discounts (obviosly a Rolls Royce PR
statement, but nonetheless interesting).
I didn't find out any facts about some of their bigger products, because I did not see the assembly of them. Overall the assembly of jet engines is a lot lower tech than one would assume. The Tay engines are made on a shaft that is in the middle of a room that goes up and down as individual people basically piece together the parts that they make for it. There is no assembly line or anything like that, just a lot of precise engineering going on to design and test the engine once it is "pieced" together. This process is expensive and time consuming, which makes the costs of the engines very high.
Also the development for a new engine is a huge ordeal. I also got to see the experimental lift fans for the new Joint Strike Fighter, and they have destroyed many in testing in order to fully design them. The engines are by far the most complicated part of any jet aircraft. But they are made well since they are so rigorously tested, and rarely are replaced except on very old models. Current jet engines are so well designed that they can have lives that exceed the airframes that they are placed on. If the maintenance is done correctly, the useable life of an engine is over 20 years. Maybe someone else can give actual numbers for hours of life that some engines actually get. The maintenance overhauls and spare parts are where companies like Rolls Royce make a significant amount of their money. Jetsgo just recently signed a $90 million contract with Rolls Royce for the engine servicing of the 18 Fokker 100 jets engines that they operate.
If you have never designed an airplane part before, let the real designers do the work!