gforce 6800 vs newer models

Alright, so about 5 or 6 years ago, I bought a evga nvidia gforce 6800 video card. It was pretty much top of the line when I got it.

Lately, i've been bugged by my single core processor and want to upgrade, but to do that, i need a new motherboard and i'm finding that many motherboards don't support agp (which is what my card is) anymore, so I think I may just upgrade to pcie.

In researching new cards, I've found cards like the gforce 8600. Not top of the line, but still seems very good.. an upgrade in most cases as compard to the older 6800 i have (despite it being slightly lower end). However, the prices for my card are still in the hundreds: eVGA e-GeForce 6800 Graphics adapter - 128 MB - DDR SDRAM

while I found the 8600 for only $35 here!: eParts and More

So whats the deal. I compared some of the specs based on this: Comparison of Nvidia graphics processing units - Wikipedia, the free encyclopedia
and the 8600 looks better in almost every respect. I'm no techy, but am I missing something? Any suggestions? Thanks :)

Let's check for GeForce 6800 and GeForce 6800 Ultra.
GeForce 6800 card requires only one direct power-supply connection, and it also takes up the space of a single expansion card, while the 6800 Ultra requires two power connections from a dedicated cable.

With respect to speed, the GeForce 6800 Ultra runs at a core clock speed of 400MHz and a memory clock speed of 550MHz, compared to the 475MHz core and memory speeds from Nvidia's previous high-end card, the GeForce FX 5950 Ultra.

The GeForce 6800 graphic card supports the next-generation pixel-shading technology; faster, more-realistic shadow rendering; and other advanced technologies are also impressive...

Oh okay, I see what your saying, so models like the gt and ultra are significantly improved over the standards in these cases, and the high prices i'm seeing are for the high end models of the 6800.

Okay so just looking at the 6800, which I have, would you say a card like the 8600 would be a good choice of upgrade for the price? Not speaking to anything fancy. Basically I want a card that can handle some newer games and such but nothing top of the line because i'm not willing to spend hundreds again and I don't keep up with games or demanding media like that. And I was hoping I could upgrade to a more powerful card for less than $100, banking on the fact that since I waited i could get a good one for cheap. Any other suggestions?

by the way, thanks for the quick reply! I'm sure you guys get dumb dumbs like me asking simple questions all the time, but it is very much appreciated