Hi Bernd, nice to hear about you, and better that you´re from Austria (my backround is from there, though I don´t speak german :-) ), I got confused with your spelling, :-) just a joke.
Well, there are a few good places in Santiago.
If you are in downtown, you can go to:
Berlin Hobbies
Jugueteria Alemana
They sell mostly Italeri and Revell of Germany, Tamiya, Academy, Zvezda....... I´ll send you a private message m with the adresses.
If you are in Las Condes or near, you can go to Mirax, in Apumanque Shopping Center. It´s the biggest store in Santiago, so you can find almost everything you want in kits, but only few thing in aftermarket and dioramas. Also, in Las Condes you can find in Mall Sport Shopping Center another store from Jugueteria Alemana, but is most orientated to trains and stuff like that. But you can find armor, planes and ships as well.
From Internet, you can buy from
www.solomaquetas.com,
www.mirax.cl and
www.hobbyexpress.cl. All of them are from Chile and are safe and fast enough..
Well, hope that these info will be helpful for you. If you need more info, let me know by private message or e-mail me.
Bye and best regards.