Yea airBnB is overpriced in Prague, so ~ 50% off is fair.
I never liked P-3 ... I lived whole time in P-7 which is ideal imo. Five minutes by tram to the Old/New Town, heaps of restaurants, cafes, supermarkets. Two parks close by, cheaper rents than P1/2/5.
Also if you like night clubs - and I mean real night clubs, not the dump for tourist in P1 than most of them is in P7 as well.