Is there anything about B-52's that doesn't cost a fortune?
Then again,they have been in production for so long now that there is a ready supply of replacement parts,and the USAF hasn't even tried to replace them because they just can't find anything that would work better.
AND......,it is a hell of a lot cheaper to manufacture parts that you have been manufacturing for decades than it is to tool up to manufacture spare parts for brand new series of bombers.
Frankly,I can't imagine a better or more efficient design. If there was one,the zoomies would have been demanding it be put into production.
If it ain't broke,don't try to fix it.