Hi dude, welcome aboard.
Your bike is rideable for a start. As you get better you may want to upgrade parts. An alternative to bars and stem is bar/stem combos, like Sequence and swissmiss, both have minimal offset.
Being from Argentina, its harder to buy stuff second hand because paypal is the most used method of payment, but you can pick up good deals here in the marketplace, and e-bay too has good deals sometimes. Also online stores have sales which save you a bit of money also.
Its just a matter of looking around in various places, buying used parts instead of new, and doing it gradually. You may find local riders in Argentina have stuff for sale too.
All the best. Cheers.