A friend of mine recently gave me a set of Infinity bookshelf speakers but the 8" woofers in them are blown (lots of rattling when they hit a bass lick). The tweeters and mid range drivers are still in excellent shape and the wooden cabinets are in perfect condition. Where can I get some good but inexpensive replacements for the woofers? At one time these speakers were pretty expensive (when they were bought 7 years ago), and I figured they'd make a nice gift for my nephew who's about to turn 16 and is building his first system.