Your best alternative is to use
the Classified in the List?n Diario.
There are always offices being sold. Desks, file cabinents, computers, faxes, the whole thing.
The place you went is a bit pricy. Perhaps you should look at
Funcional on 30 de Marzo across the street from the Parque Duarte (next to the Cathedral?)..They have their own office furnture factory.
FWIW
HB