I advertised mine on preloved and snagged people on here who were looking for ratties

Through email ask them lots of questions if they respond to your adverts, such as what type of cage they have and what bedding they will use and what food they will feed. Make sure they really know their stuff before they go to new homes. Personally I won't sell my rats to anyone who I don't like the sound of, or who doesn;t know their stuff or is obnoxious or rude about answering questions.
Another important question to ask is WHY they want rats. If it is for children (It is coming up to christmas after all) I'd be hesitant to sell them to that person. If they are for kids, ask to meet the kids and parents first and make sure the kids know what they're doing and that tyhe parents are happy to take on the responsibility of having them if or when the kids get bored of them.
If you have any questions just PM me
Peace
Akai-Chan