I've used research Now several times and found them excellent. Because I survey very specific populations, the cost per respondent is probably not relevant. However, I have obtained quotes from both Qualtrics and RN and find RN much more competitive. We have always found their support services excellent too. We've only used the New Zealand operation, but I would be happy to recommend them to others.

Following up on this: I ended up using ClearVoice Research. Their customer service was fantastic, and the pricing relatively affordable. The data I collected ended up being subpar, probably due to the fact that my survey was on a sensitive topic that required reflection. Unsurprisingly, participants seemed to be racing through the measures and not giving items much thought.