I started out with the Celestron NexImage camera. I then moved on to the ToUcam. Now, I'm spending an increasing amount of time with the DMK.
All I'll say about the NexImage is it's a nice, easy way to start out. Everything you need is right there in the box...and it's just a case of installing the software on your laptop...plugging in the camera and away you go.
Having said that, the results are not as good as the ToUcam (IMO), which really isn't that much harder to operate...if indeed it is harder to operate.
The DMK??? Well that's another beast entirely and another step up from the ToUcam in terms of quality, which is a step up from the NexImage.
DMK = Great camera, great capture software, but (as the guys have pointed out) there's a lot more processing involved if you buy the mono (black and white) version and intend to create colour images (of the planets).
Like most things in life, you get what you pay for...and the results are usually directly proportional to the time and effort you are willing to invest.
To cut to the chase, I'd highly recommend you get yourself a ToUcam, 1.25" adapter, IR/UV filter and download K3CCDTools and Registax (capture and processing software).
Good luck with your decision.