how can i buy this font?
i want to buy this font.

You can't buy the Andes which is a Fantazia copy of the Plaza SH [ http://www.myfonts.com/fonts/efscangraphic/plaza-sh/regular/ ] which you can buy for $26.
Another copy, which you also can't buy, lives under the name of Andesite, the Regular, 1991 James M. Harris and the Plain, 1991, Atech Software - famous font cloners that have been in business for many years under many different names.