The 505 isn't shown on the RCBS website any more, so it sure sounds plausible that they've discontinued it.
I used an RCBS 502 for 20+ years, but since that one is a 2 poise design the markings are really close together and it's easy to accidentally set the counterweight 5 grains off. The 505 is a three poise system and the counterweight positions are much more widely spread. My 40-something year old eyes just can't make out the divisions on the 502 any more, so I picked up a 505 simply as a self-preservation measure. I figure I'm much less likely to end up with an over/under charge that way.
$50 is a smokin' deal, hopefully PSA doesn't try to make it up on the shipping charge.
9 bucks or so was the freight for me