all dart frogs will climb if ou give them the chance, but the easyest arborual ones are Dendrobates pumilio- these guys are about $150 each!
Dendrobates imitator-about $50-$100 each
Dendrobates intermedius- another kind of imitator about $100 each
Dendrobates fantasticus-about $120 each
Dendrobates reticulatus -about $150 each
if you are jest gettign into dart frogs i would stay away form the true arboreals, you can put just about any other dart frog in there and they would do fine, just make shore you put in plenty of epyphitic sp? bormiliads!