They seem cheap. Labor intensive, particularly the sanding and polishing part, but cheap is good. I have time, particularly if my wife isn't going to get a job this summer ...
The biggest issue you'll run into doing concrete counter tops is that they have a tendancy to crack if you don't use the right mix and do them in place. Failing to put in rebar (this should be a no brainer but it happens) will also lead to failure. Honestly, with the amount you'll spend on concrete and the not insignificant risk of it cracking (total replace) and failing you'd be better off getting high quality butcher block. The nice thing about butcher block is that, in addition to being cheap (~$300 for a kitchen your size), when you go to sell it and you want to upgrade it's a quick rip out and won't damage your cabinets. Good luck doing that with concrete.
