Bought an Olympus D620L 1.4 in New York just over 12 months ago, cost 900USD, with an extra 32Mb memory card. Great resolution for 6x4's.
The only thing not discussed by anyone here is the real point of the matter-Resolution!
What do you want to use the camera for? Just to put pictures on the internet? For the best quality print you can get?
The above answers will determine what resolution of camera you need. A 6x4 photo printed on a good quality inkjet with the proper paper will look better at 1024x768 than at 800x600 resolution. This relates into the "Megapixel" hype. The lower the pixels, the lower the resolution, the lower the price!
If you want the best photo prints at A4 size, you get the most pixels your money can buy. Remember, while the quality of 1024x768 is OK at 6x4 photo paper size, it degrades as you enlargen the print size, as the information for the extra space is 'filled in' using algorithms of the software.
Generally, 1024x768 (1.4/1.6 MegaPixel) is good for a 6x4 photo, but if you want larger prints, go to a 2.1, 2.5, or even a 3.0 for A4 prints. Photo prints look pretty ordinary at 800x600 and below compared to proper developed prints, believe me.
Hope this has cleared the mud some.
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When all else fails, read the manual!