Nikon D5000 /D7000 portrait?

Hello , i need to upgrade my Portrait with Nikon D5000 such as using a prime lens 50mm 1.8.
Do you think i have to use better body such as Nikon D7000 which has better sensor.
Nikon D7000 now cost about $1100 but in ebay with positive rating 99.1% now cost $900 but im affraid of the increasing No .of defects and loss of reliability by buying from ebay..

2012-11-27T17:01:40Z

i need to get sharper images with better contrast.

keerok2012-11-27T21:59:07Z

Buying a better camera or lens won't help much. Sharpness and contrast is mostly up to you. The camera and lens are only tools.