Id.; see also, Ledbetter v. City of Topeka, Kansas, 61 Fed.Appx. 574 (10th Cir. 2003) (affirming denial of motion for voluntary dismissal without prejudice, which was filed more than a year and a half into the litigation and after discovery, motions, and a pretrial order, because of prejudice to the opposing party, including the expense and effort in preparing for trial, excessive delay and ins