Some sellers are now selling refurbished Nikon D5100 cameras (body only) for under $500 (B&H through eBay, KEH). As you know the Nikon D5100 is no slouch and uses the same sensor as the best Nikon APS-C sensor used in the Nikon D7000.
In case you're thinking about getting a D5100, here is a brief comparison between the D5100 and D7000. First, the similarities:
- Same kick-ass 16mp sensor with very low noise and wide dynamic range
- Same ISO range (100 to 25,600).
- 3" 921k pixel LCD screen.
- Both capable of 1080p video at 24fps.
- external microphone jack
Here are some of what you're missing with the D5100 compared to the D7000:
- D5100 has only one command dial. D7000 has two.
- D5100 doesn't have direct access buttons for ISO, White balance or file quality (JPEG, RAW, etc.). You need to go through the menus to change those settings.
- D5100 has only one memory card slot. D7000 has two (the second can be used as backup or overflow or for video).
- 95% viewfinder vs. 100% viewfinder
- 11 AF points vs 39 AF points
- The D7000 has a more advanced AF module.
- 420-pixel Matrix Metering vs. 2016-pixel Matrix Metering.
- 1/200 sync speed vs 1/250 or 1/320 sync speed
- D5100 doesn't have a commander mode
- D5100 can't do HSS.
- D5100 has no built-in AF motor. Some older lenses will not autofocus on the D5100 (although there may be focus confirmation through the electronic rangefinder).
- 4fps vs. 6fps continuous shooting
- 16 scene modes vs. 20 scene modes
On the other hand the D5100 has a few advantages over the D7000:
- Swivel/tilt LCD screen. Can be used for unusual angles or for self-portraits.
- D5100 can do 1080p at 30fps. D7000 maxes out at 24fps.
- HDR mode. The D5100 can take 2 shots and automatically generate an HDR shot.
Although the D5100 is missing some features from the D7000, it is still a pretty good camera. It's hard to beat for $500. Note however that the price may have decreased because the D5200 could be coming soon.