Default pleasehelp

ok ill make it straight forward .
i'm frm india ! htc one over here costs around 40000rs (600$)
i recently came to know that htc one costs just 100$ (with a two year contract) in usa
my dads going to usa next week . so can i ask him to buy a htc one from at&t (fr exmple) using his international visa credit card .
and then im planning to unlock it using third party websites(without paying in full)
is it possible >? hoownto do it ?
will there be any problems to my dads credit card ?
will they automatically detect the penalty frm my dads credit card ?
or where can i get htc one cheap ?
please help ?