Help Please-Tipping Advice

A florist who I have not yet hired has offered to make me a sample centerpiece, free of charge. I'm not sure if she's giving me the centerpiece to take home, I haven't asked. I think it's out of the ordinary that she's making the sample without being hired in the first place, so I would feel pushy asking if she's giving it to me.

I want to tip her for making the sample, and especially because I would feel bad if I didn't love it or end up hiring her. I think the tip should be more if she is actually giving me the sample to take home. What do you girls think would be an appropriate tip for if she is giving the sample or not? Thank you!