dinan is only worth the price IF it is used. if it was brand new, then its more expensive, the best thing about DINAN aftermarket products, is that they are warrantied through DINAN and BMW, all of the other aftermarket products are only warrantied through the manufacturer. the JC CAI is a nice CAI, I heard that it give close to 20hp (not sure if it is at the crankshaft, or at the wheels) if you want to find out more, your best bet is to go to
www.bimmforums.com/forum and then click on the "bimmer cars" thread, and then search for the dinan CAI for sale, or the JC CAI for sale, im sure you will find a couple of threads that have them on sale, good luck in finding them.