The Armada AR7 is one of the lightest most durable park skis. Moment is making some amazing skis but they are heavy, certainly durable though. From Line you would want to look at the Anthem or Afterbang. If you are looking for value it is hard to beat the Line Afterbang especially older models.
Line Afterbang w/Salomon Z10 $350 - http://www.untracked.com/p4476-12_line_afterbang_skis_w_salomon_z10_ski_bindings.html
'12 Afterbang w/Binding Options - http://www.untracked.com/p4205-12_line_afterbang_park_freestyle_skis.html
+ 1 for AR7's