i hope you meant 350 each. Becasue if its 350 for a pair 1. it might be a scam. 2. There probably not new. 3. somethng wrong with the subs. And yeh those are some awesome subs.
The 15" 3500 series retails for $379 new, so you're doing pretty good for them saying they're $350 shipped. The 3500 series is basically a little brother to the 9500 series, they are excellent subwoofers. You really can't go wrong with Digital Designs, unless you just hate ported boxes (which these subs are mainly optimized for).