How much can a bad alignment drop your mpg's?

The past few months I've been noticing a drop in my mpg's. I also have been noticing that I need an alignment but need to by the new ball joints before I do so. I have been having some front tire wear / etc lately and got me thinking maybe the alignment is causing my mpg's to drop. I filled up today and got a little less then 15 mpg's. Tire pressure is ok, clean maf, newish plugs, etc

Any comments on the alignment / mpg thing? Could my timing be off?

 

Since a bad ball joint and alignment can be dangerous I would get them fixed ASAP. See what happens with the MPG. I have a feeling that something else is going on.