glaswave, thanks a lot!
i guess u are in most quotes right. i guess it´s easy and cheeper to do it that way, but should only be done with cheep bikes because of the hassle you can get into when you never get it registered properly into your name.
i tried to get hold of a bike, but there were only a few around and i seemed to miss them all.
In the meantime i bought a klr 2010, chile-registration, fully equipped, for 7000$, looks brand-new

the registration in chile is really easy, u just go to sii (tax-office), ask for a rut (tax-number) then go with the seller to a notaria and they do all the paperwork, done in 3 hours. costs approx. 200$, depending on the value of the bike. i guess the sale after my trip (approx. 15.000 km) will be not that difficult either.
for the zona franca: as far as i know now, you can buy a bike there but as extranjero u are not permitted to enter chile outside the tax-free zone where it´s registrated. i guess there is now checkpoint inside chile (iquique in the north and arsen in the south), no problem as long as u don´t run into a checkpoint or want to leave the country at a bordercrossing outside zona franca. and u are not permitted to leave the zona for more then 90 days...
if someone is interested, there is a great bike down in puntas arenas right now, fully equipped, for 5000$, chile- (zona franca) or us-registrated. it´s in the thread bikes sell/wanted. the guy who sale it is really nice and helpfull. but u have to ride it back or to the us (or sell it on

).
if anybody is in argentina (medoza.salta)/bolivia (uyuni-cusco) right now, i´d be happy to meet for some

and some news!