any tips on negotiating with a provider hanging at the video poker machines?  like, what to say or not say and a starting price.

Just make eye contact, say hi and smile. If she talks to you, she's a provider. Just chat her up a bit, and then ask her if she is working. If she says yes, ask for a menu, then let her name the price. Aim for $300, especially later at night, say 1:30-2:30 in the morning.