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That is probably the best price you are going to find. The AIS system is expensive and the replacements are VERY F'ing Expensive. That is the price of a great filtration system.
If you want some noise and cheap replacement filters then purchase the 6637 Kit and put a Pete's Cover on it.
From some reading I did several years ago, IIRC, the Donaldson PowerCore technology used for the AIS (and other PowerCore element configurations) are supposed to be good for about 100K miles. Of course, just like with ANY air filter, the useful life will depend very highly on the type of ambient air conditions you drive in (amount of airborne dust/dirt).