We have a store here called BiMart, they sell pure one pound zinc electrodes in the fishing section for fishing weights,check your fishing stores, as mentioned electrical conduit connectors, or even used battery's.
http://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_battery
http://www.google.com/#sclient=psy-ab&q=zinc+electrical+conduit+fittings&oq=zinc+electrical+conduit+fittings&gs_l=serp.12..33i29i30l4.3992.20139.0.26542.36.30.0.5.5.5.1082.8359.1j16j5j2j2j2j1j1.30.0....0...1c.1.22.psy-ab..8.28.5651.hwuZbAqBypI&pbx=1&bav=on.2,or.r_qf.&fp=832001f40853dd3b&biw=939&bih=563
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http://en.wikipedia.org/wiki/Zinc%E2%80%93carbon_battery
http://www.google.com/#sclient=psy-ab&q=zinc+electrical+conduit+fittings&oq=zinc+electrical+conduit+fittings&gs_l=serp.12..33i29i30l4.3992.20139.0.26542.36.30.0.5.5.5.1082.8359.1j16j5j2j2j2j1j1.30.0....0...1c.1.22.psy-ab..8.28.5651.hwuZbAqBypI&pbx=1&bav=on.2,or.r_qf.&fp=832001f40853dd3b&biw=939&bih=563
http://www.google.com/#gs_rn=22&gs_ri=psy-ab&gs_mss=zinc%20electrica&pq=zinc%20electrical%20conduit%20fittings&cp=10&gs_id=242&xhr=t&q=zinc+fishing+weights&es_nrs=true&pf=p&sclient=psy-ab&oq=zinc+fishi&gs_l=&pbx=1&bav=on.2,or.r_qf.&fp=832001f40853dd3b&biw=939&bih=563