Rm500 for apartment staying 6 persons the price is reasonable. But where is it? Walking distance to subway station. Or near the tourist spot. This would be the few critical requirements for u guys.

Guesthouse might be slightly same or cheaper depends on which area or room type. When are u going? Personally suggest u can make reservation early if wanna book guesthouse. Reason why is not much guesthouses are providing rooms with 5 or 6 persons. Sometimes it might be quite pack or sometimes are very empty.... Hahahhaha.