5850s

And people are RIGHT NOW bidding 5830's up to $160 on eBay -- at least that's the going "market rate" on eBay for them. Which is ridiculous -- anyone hoping to MAKE MONEY is going to be disappointed, because you'll never see $160 from one of those cards. A person would be better off buying $160 worth of BTC.

5830s, unlike 5850s, do NOT get 0.25 BTC/day.  5830s only get 0.167 BTC/day.

Now if it wasn't $160, it might be an OK deal. Perhaps $130 at the absolute highest.
Really, what made the 5830 popular was the $110 price point. It's NOT the ultimate card for Bitcoin mining. There are plenty of cards that mine better than that card!

When I see people bidding the 5830 up higher than a 5850 or 5870, I have to shake my head. The 5850 gets about 350 MH/s and the 5970 gets about 365 MH/s, with moderate overclocking (no voltage tweaking).

Unfortunately, the smart people figure it out first, followed by the pretty smart, followed by those of average intelligence, followed by those of below-average intelligence.

Not everyone "figures things out" at the same time.

Just like with the Dot-Com bubble, just like with house flipping. There were some people who didn't know the bubble burst even after it burst! They still thought the bubble was intact (rather than burst). Those people, of course, lost plenty of money.

You want to be one of the quick ones -- one of the smart ones.