Seconded/thirded/whatever, wait until Black Friday. You will mostly like NOT get a PS3 for less than $300 that day, but you will get the most bang for your buck with all of the bundled goodies. Last year Gamestop, Wal-Mart and Best Buy all had good bundle deals (two fairly recent games, maybe The Dark Knight blu-ray, and maybe an extra controller -- depending on your bundle choice).
For me, though, the best was Hastings. It was $300, but I got Uncharted and InFamous (both had recently been released), plus an HDMI, plus coupons for free game rentals, half off third party controllers and accessories, and a coupon which let me pre-order a game for free (and also netted me a $10 giftcard for using it). On top of that, most of the Hastings employees are high schoolers and just don't give a crap. Most of my free game coupons were scanned and returned, letting me reuse them until they expired.
Also, once a year Hastings has had 30-40% off all used items. Last year I remember a guy in front of me bought a used slim PS3 for $175 or so. This was a few months after Black Friday though.
Anyway, long answer short, Hasting brick and mortar is my recommendation.