ANT offers a system (EEGO is the name I believe). Also, there are some wireless systems too from some folks I know. I suppose it depends a bit on how many channels of data you want and also what kind(s) of movements the participants will be making.
g.Nautilus seems to be good choice, and I agree with previous suggestions. However, for me, I believe that the most important is consider having a strong fixed EEG cap with reasonable number of electrodes (e.g., 64 or above ). In addition, you need to pay attention at preprocessing stage as you'll have many temporal muscle activities.