What cameras are best at handling high ISOs?

I'm looking to upgrade my camera and, as I often shoot in low light or situations that require a higher ISO, I'm looking for a camera that handles high ISO's very well, with as a little noise as possible… I know the D3/3s/4 are great for that BUT I'm not looking to spend quite that much on a camera, even used they're going for over 3k and I just can't afford that. So I'm wondering if you guys may have suggestions for me on cameras that are great with high ISO's! I'm NOT a professional photographer but photography is my main hobby and I take it very seriously, I may try to go pro in the future and want a camera that a professional would use.
I'm only considering Nikon as that's what all my current gear is and I'm happy with it.
Thanks!

Added (1). TheFlow - "What can you afford?"
I have no set budget right now, and I'm willing to spend time saving up for the right camera.So, I'm not sure.

So you can't afford $3k+ cameras, but what can you afford?

For low light and fairly affordable, the Nikon D5200 has an ISO range of 100-6400 with up to 25, 600 expanded, for only $800
http://www.nikonusa.com/...D5200.html

I recall a question just like this coming up a couple of weeks ago.

Anyway, have a look at a used Nikon D700.In terms of image quality and ISO performance it is exactly the same as the D3. The only real differences are in total weather sealing and FPS performance, in which the D3 is superior. You can also stick a battery grip on the D700 which makes it 98 per cent identical to the D3. I've used a D700 before and got pretty decent shots at ISO 6400 in bad mixed lighting. You can push it higher than that as well if you really need to.

Something like that kind of camera and a fast prime lens, and you should be on the way to low light/ high ISO fun and games.

Http://www.dxomark.com/index.php/Publications/DxOMark-Reviews/Nikon-D800-Review

Consider the D800. I believe it's got very good high ISO performance.