I have Nexuiz. The community on it isn't completely dead yet. I got it for 200 (which i assume will be the price again) and it is well worth it.
Having played the demo to Voltron, i'd say it's worth about 200 too. But no more. There are much better shooters in that style.
Kill Team is pretty good as well. It's worth 400 for someone who likes that game style and worth 200 for anyone else, easily.