I know someone who has done something similar, though not with a studio. He started off living in his apartment (i.e., didn't buy it just for the garantia) but has since moved to bigger place (a house - his needs grew with his life) and is planning on renting out his apartment.
But you have to be very careful renting out your apartment on a temporary basis. A lot of potential problems, not a simple thing to just rent it out and forget about it. And if you hire a company to manage it for you, you lose a portion of the rent to the management company. You also become a possible target for AFIP nowadays, particularly if you sell your apartment in the future.
If you intend on renting the place temporarily, make sure you buy an apartment in an area that tourists will stay.
And if you do so, I know a guy (US expat, Argentine wife) who manages temp apartments and has a high percentage of time rented for those he manages...
Rich One, I don't know about there being a comparable value on garantia property. I've never had that problem - I've always rented an apartment (and once a house in the 'burbs) way above the value of the property that was used as the garantia. Remember, a garantia is not required legally, there is no real law that I am aware of reglating what sort of living space can be used as a garantia - it's all about what the owners will accept. I've used a small apartment in Cordoba as a garantia to rent a 220 sq mtr house out near Pilar in a closed neighborhood and a small vacation rental in Mar del Plata to rent my current apartment.
As far as the garantia in your name - that is a good point. You may have a lot of difficulty finding someone to accept a garantia in your name. My friend actually rented the new place in his girlfriend's/future wife's name and used his property. Hadn't thought of that...
As far as a cochera - that won't work, I don't believe. It has to be a dwelling as I understand, though I could be wrong about that.
