When I put my house up for sale I already had a price in mind of what I would accept. I had a few low offers. I know Estate Agents over value. I also had everything in place pre listing it for sale and knew where I wanted to move too. There's nothing worse than putting a good offer in on a house and waiting days for a seller to get back with an answe. Its not as if you move in the same day, it takes weeks. When someone put an offer in I dealt with it then or let them know the next day.
Why do some sellers wait ages to get back to you. I'm currently on day 2 of waiting to see if my offer is accepted.