Here's a great way to respond.
She asks you to buy her a drink?
You say "You want a drink? Okay, my friend over here will buy you a drink watch. When I introduce you to him just act really quiet and shy. After he buys you a drink you tell him that there just isn't a spark there but it was nice meeting him."
So you pick some chump out and lead her by the hand over to him. Introduce yourself first and tell him that your friend Sally here has been bugging you to introduce her to him but she's a little too shy to talk to strangers. "Will you talk to her please?" Introduce Sally and lead her right next to him with your hand. Say you two look so cute together, I've got real good feeling about this one.
Then just walk away. If chump buys her a drink great. If not who cares.
You're achieving a lot of things with this approach. Most importantly you come of as a challenge and an Alpha male. She's giving you a big sh!t test to see if you will supplicate. You pass by not even taking the test! You acknowledge her testing you and then pass her bullsh!t onto some other sucker who will probably fail. She'll be back to you as soon as she gets her drink from the chump.
However you should seriously be questioning why you should waste another minute on a creature such as this. Sex is the obvious reason I guess.