I am impressed on how the rate of bikers trying to sell the bikes in L.America has triplicated in the last couple of years. Many think that is practical and easy way toy sell it. Well unless you are doing arrangements way before your trip ends, fine but, while you are there and pressured to sell before you come back is even worst.
Selling in Argentina is not easy today. Bikes must be new and if a local is willing to buy, it would be under the table. (unlawful deal) , exposing you to be banned for life for not closing your Temporary admission.
Selling the bike to a tourist is ok but then USCustoms will notice it at the time of reentry and penalties and duties willl be imposed .
Chile is impossible unless the bike is sold at 'duty free areas' . Bikes should be new for import. Also, Chileans don't have the money to afford big bucks and a complicated negotation, unless you lower a lot the sellling price. Yuo should also close your Temporary admission as the law mandate.
Peru, Bolivia and Paraguay are the only one still allowing used bikes but, then again is the selling price what interest buyers. Forget $7000 for your bike, nobody is going to spent that sum unless is a high end bike over 1000 cc.
I 've just offered a BMW 1200 for $8k bucks in Bolivia and no one was excited. So figure out.
If you have 2 weeks time frame, unless you sell the bike for $3k, probably it would work. Don't waste your time traveling all the way up to Paraguay or Bolivia looking for a buyer, then it will be be even more expensive shipping and flying you out of those countries.
As a final comment , don't play the Cassidi and Sundance way to get rid of things. Assume your export and live with it.
Every time a tourist sell a bike under the table and go away, it is one negative point on that particular country for all other foreign riders, why? because these countries start getting tougher on the law about temporary admission and imports; eventually they could ask even for a bond in the future, and no one want that.
I have seen how lately , some riders wants to sell in Punta Arenas (Free duty in Chile). it is becoming the paradise for many in Patagonia. Nobody knows how the deal is managed but, I think, somehow over the time the law would change and everybody will be affected.