try ebay. Find someone with a good price and then send them a message with an offer to do the transaction through paypal outside of ebay so they can save on fees and pass said savings along to you. I did this and got my $650 magnaflow for 500 shipped.
I have a gibson SS muffler sitting around in my storage. Every day I debate putting it on but I dont want it to be as loud as my 98 was with a Doug Thorley cat-back system with a high flow cat. RICEANDPHO put up a good video of the gibson system in a v6 and I like the noise when he punches it but I have no idea what the cruising noise level is so I've been too worried to put it in.
I got my muffler for $30 shipped off ebay. Came from a guy who bought the gibson cat-back for his ford ranger but thouhgt it was too loud. I randomly bid about 7 bucks on it one day and a few weeks later I got an email saying i won the auction, it was a crazy surprise.