Millennium Technologies quoted me less tan $200 for plating, they also aluminum sleeve cylinders, they only done my 4 poke cylinders so far, but i was looking when my LT500 cylinders hit 88.5mm having them plate over the steel to run 88mm pistons. The thought processes was at 88.5 mm the cylinder has enough meat in it to keep from going egg shapped, seen too many 89 - 89.5mm bored cylinders and are way too thin.
 They claim on plated cylinders is that you should be able to run at least 2 pistons life as long the coating is in good shape. ( no flakes, cracks,)
http://www.mt-llc.com/