1.
If someone talks up a particular thing, they make it sound more interesting, valuable, or likely than it originally seemed.
Politicians accuse the media of talking up the possibility of a riot...
PHRASAL VERB : V P n (not pron) , also V n P
2.
To talk someone or something up in negotiations means to persuade someone to pay more money than they originally offered or wanted to. ( mainly BRIT )
Clarke kept talking the price up, while Wilkinson kept knocking it down.
PHRASAL VERB : V n P , also V P n (not pron)