I've seen maid Robots selling for 800,000 Gold before.

I suggest first getting 800,000 or 1,000,000 gold then start looking around at the stalls that people sell things with. Occasionally people will sell them.

Also when you are searching for the Maid robot you can use the world chat to see if anyone has one for sale and ask them to PM you their price.

I intend to buy one eventually but I don't like how expensive they are in the IM...