I don't have anyone to recommend, but I did do part-time cleaning for income before! The charges are usually $10-15/hour, but do keep in mind that you have to avoid domestic helpers on their off days because they aren't allowed to be doing adhoc after. As for the duration, usually most helpers do not take any jobs less than 3 hours or so - because you have to factor in their transport and travelling time too :)
Hope you find this helpful: http://www.a-team.com.sg/house_cleaning_services.html
$15/hour. Usually is 3 or 4 hours per slot
$12-$15
It is $15 per hr. I am also looking for one.