VicOsaki: there seems to be real misunderstandings.

I can buy tickets (for the local prices) from anywhere in the world ... if I start actually my trips (on that ticket) from that specific country.

The 'trick' is to combine two (or more) rtw-travels and use only one of them from your original country (book the first and last segments of all trips to that ticket, and all other rtw-tickets you buy from a cheaper/cheapest place 'en route' and you fly those segments in between). To be on the safe side (reservations, upgrades) you can book/confirm/prepay (with your crdit-card) rtw-tickets 2 & followings from an airline or a travel-agency in that 'low-cost'-country and either let the tickets be delivered by mail to your place (or if this is not accepted by the airline) have the tickets ready to be picked up once you arrive there.

It can be done ... it has been done ... and I am still doing this