I dealt with "Al-Jasem" Agency.
They are near passport authorities in Medinat Khalifa.
If you are coming from Markhia roundabout (this is the roundabout after TV round about directly), don't go under the tunnel way, go to the roundabout just below the bridge and above the tunnel and go straight forward.

You will see the passport authorities at your right side followed by a gas station. Go forward slowly for another 500 feet, you will see some barbershops at your right.
Ask for the agency, it is in the 2nd floor.

I paid a total of 6,500 QAR for a maid from the Philippines. But this price is from last year.
Currently, you have to pay 8,000 QAR for maids from Philippines.
The cheapest are from Nigeria and Indonesia (6,500 - 7,000 QAR).
If I remember well, I think this includes the 1800 QAR fees but I am no longer sure. You should negotiate the price anyway.

If you are non Muslim, I would advise to get a christian maid from the Philippines.

Whatever you get, try to have someone who needs the money and certainly not single. Avoid those with previous experience in the gulf, as they tend to be lazy and not very clean and want other maids to be around with them to chat.

If and when you bring a maid, do not be too generous. They take this as a sign of stupidity not goodness!
Tell her your rules in the agency before she goes home with you and some rules you should always apply are:

NO MOBILE PHONE! She can call occasionally from yours to her homeland and you can deduce the expenses.

NO GOING OUT OR HANGING OUT IN DOHA WITH FRIENDS. These only tend to tell her how to get more out of you for less work.

I have had the above problems and they have ruined our relationship with our maid, leading her to hit one of my daughters and screaming at my wife, for which I put an end to it by sending her back. It was her wish at the end and she got us to do it...!

Good luck.

Should you need any further help, please don't hesitate to ask.