By far the best price I got was at Performance Peddler. Go here:
Hover over Add to Cart but don't click. A popup should appear asking you for your email and best offer. Put in like 50 bucks. You'll get an email with their best price and a link to buy it for that. It takes a few min for the email, be patient. I just tried it for your muffler, the price they sent me was 149.41.
EDIT: They don't actually send a link, so you can click the above link, add to cart, and enter the discount code bestoffer4, that'll give you the price I said.
I bought one for my car last year from them, it's for real.