Eight kilometers west of Ushuaia [1] on the road to Lapataia, the free Camping Municipal has limited facilities (fire pits and pit toilets only). A stiff climb to the northwest of downtown, La Pista del Andino (Alem 2873, tel. 02901/435890 or 02901/15-568626, www.lapistadelandino.com.ar [2], US$4 pp) has slightly sloping campsites at its ski area; the first transfer from downtown or the airport is free. It also lets guests with sleeping bags crash in the refugio above its bar/restaurant, but this is less than ideal for anyone expecting to get to sleep early.
Links:
[1] http://www.moon.com/destinations/chile/southern-patagonia/ushuaia-argentina
[2] http://www.lapistadelandino.com.ar