Marcello,
If you know any specific titles, I may be able to find them used locally and shipping is about $8 (30-40days by slow boat) or $15 ( 7-14 days buy US postal air) give or take depending on th size of the shipment. That is for about a 1-2 lbs book.
By good fortune we have about 4 bookstores in Omaha and Lincoln, that have a very good inventory of used phtography and art books. You can wire funds through your bank. There is a surcharge on transfers but it may be a cheaper option then ordering retail because sending a personal item skirts the taxes or VAT or whatever you have where you are.
Anyway just an idea, I am at the stores about twice a month and get calls from owners when they buy large lots from estates. so it is really no trouble.
Jim Chinn