Here are some other constructions you could use:
Cad é ba chóir (or "ba cheart") duit a cheannach di, dar leis? = "What should you buy for her, in his opinion/according to him?" You can also put "dar leis" at the beginning of the sentence instead of the end. "Dar" is a special verb, used with "le", for expressing opinions or what someone thinks.
Dar leis, cén bronntanas a ba chóir duit a cheannach dá lá breithe, dar leis? = "What present does he think you should buy her for her birthday?"
Is clos dom gur maith leat tae. "Is clos dom (go)..." corresponds to the English "I hear/heard (that)..."