The 610 Rukus is a thing of beauty. I haven't been able to find a better EDC for my purposes. The eBay prices are, as you say, up around $500, but sometimes you can find one cheaper. And they sometimes show up on the market here for a lower price.
The mini-Rukus is a pretty big knife, too, and they are a lot easier to find and quite a bit cheaper.
Benchmade also made the 741 LUM Onslaught, which is almost as big as the Rukus 610. It has an Axis lock and 154CM steel. I'm not sure about the availability on the aftermarket, but it's an excellent knife with a thin, high-performance blade. The edge width at the shoulder is 16 thousandths (0.016 inches), which is quite a bit thinner and more aggressive than almost any other EDC of similar size.
At the spine, the blade stock is 0.1085 inches, vs 0.1490 for the Rukus. The Lum Onslaught will outslice the Rukus.
The big Onslaught doesn't get much attention on the forum, but most people get dazzled by apolcolyptic heavy blade stocks and forget what it takes to actually perform as a knife.