This may help for the running belt. The shop is supposed to be in Villa Crespo, which is right next to Palermo.
http://articulo.mercadolibre.com.ar/MLA-481099454-cinturon-running-de-hidratacion-c-2-botellas-noaf-trekking-_JM
Mercadolibre is the equivalent of eBay here in Argentina, so you...