Somewhere I read that you could use peroxide in your bag when you empty it to keep the smell away. I know that I have tried it and it seems to have worked for me.
I know one morning when I woke up and emptied it I just about run everyone out of the house. Sense I started using the peroxide I don't have a bad smell anymore.
I don't know what the stuff cost that you can get from some of the supply places but I bet it isn't as cheap as peroxide. I bought an extra large bottle for $1.00.