Hi Caribbean -- I assume you're talking about a train table for Thomas the train type engines? Unfortunately you're going to find trains just aren't as popular here -- they're already fairly expensive in the US/Canada unless you get Ikea or buy used, so here they are really not seen so much -- they engines are over 100 pesos a pop, and up to 200 for some of the engines! Anyone I know who has them has brought them in from outside the country. That being said you may have some luck finding tracks and generic trains from a jugueteria that sells juguetes de madera, but your best bet is to go to Mercado Libre, the Argentina equivalent of eBay, and find someone who is dealing in trains and maybe they can source a table.
http://listado.mercadolibre.com.ar/trenes-madera-thomas
The other hope is maybe an expat who is leaving and has one to sell -- check out buenos aires' craigslist. And lastly, post it as a question in the Buenos Aires Mummy's Group on Facebook, someone on there might have some more options for importing -- but I can tell you, importing one will cost you a pretty penny.
Or a cheaper route I saw on Etsy the other day when browsing through children's furniture: http://www.etsy.com/listing/111408628/childs-train-table?ref=sr_gallery_3&sref=sr_65b2d392bf7cdc9200dca60b167ccd433ac6292de198bcb7e916c79160e049e4_1373202580_14368775_table&ga_search_query=train+table&ga_order=most_relevant&ga_view_type=gallery&ga_ship_to=ZZ&ga_search_type=handmade
(I've attached pic in case that link doesn't work)
The Argentina version of the above would be: buy a children's table / chair set here (about 300pesos from any place that deals in pine wood furnishings), then at Easy I've seen children's rugs that have the little roads all over them, staple the rug to the table top, put out your tracks, and you have a full transport table.