Okay, big subject.

First, manage expectations: anything in a hobbyist's price range will not give you Shapeways type results. I'm not saying it's not useful, but you're not going to print off jerry cans, etc without a lot of post printing prep.

I looked in them for a long time before pulling the trigger. Now that I have one, I use it all the time, but nowhere near the way I expected. I'm printing off tools, brackets, armature for sculptures, etc, but not anything that you could stick on a model without a ton of work. My hardest thing so far was a scale Japanese diving helmet, but it required a lot of texturing and filling.

My recommendation, especially at that price point is to buy a kit from a US based company like RepRap Guru on Amazon. These things need constant fiddling and calibration, so it's better to learn it all from the start instead of just staring at a paper weight. If you can't assemble one, you certainly won't be able to run one, trust me. My riprap kit went together in a few hours and gave me an understanding of the process that made printing much easier.

The Gurus have great customer service and offer all the parts which is very important. Mine was $330 shipped, but I think they're cheaper now.

It's a lot of messing around and you'll need to get proficient with Design 123 or SketchUp Make to get anything out of it but in the end it's well worth it.