If your star's day rate is $5K, instead of hiring them for only one day which might be the more attractive option, I would try to get them for 2-3 days instead.
You might get them for one extra day for maybe a grand or two on top of the day rate, or for three days maybe for $10K, if their usual day rate is $5K.
It would be a better deal for the actors since they would ultimately get more money, and instead of a quick one day job, they would have more to work with, instead of a cameo it becomes a real role for them, which most actors tend to like, since actors above all like to act.
also buyers and the eventual audience for your film have grown accustomed to the old "bait-and-switch" where they see their favorite actor front and center on the poster, yet when they watch the movie it turns out the actor only appears in the movie for like two minutes.
Getting name actors for bigger parts raises the value of your film to buyers and distributors.
Of course whoever you want to hire, before you do so I would try to inquire the buyers and sales agents whether or not they have any real value in the market place anymore.
You wouldn't want to spend a considerable chunk of your budget on an actor who turns out to be someone who the buyers don't care about, in other words "Who else is in it?".