I've been running a Suzuki Gel seat for a couple of years now.. first on my B6, then transferring it when I upgraded to the 12. I find it loads more comfortable than stock. I'm generally good on it for up to 5 or 6 hours of hard riding. Note that it also has a real leather cover, which means that it breathes better than vinyl, but also requires some occasional saddle soap or other moisturizer to keep from cracking. Also, it's a little less grippy than the stock seat.
But as noted above, they aren't easy to find. I just happened to stumble across it on craigslist. If you find one, I'd expect to pay more than $100 for it. Not cheap, but then... probably a lot cheaper than many other 3rd party seats out there.