I agree with Gold, each situation is different. 300 is a little steep, if she's super hot and you have to have it try starting at 200. You can always negotiate. Most won't turn down a guaranteed 200 from a decent looking guy with a good personality and shows them respect, treats them well.
The legit babies on here all seem to want to be handled with kid gloves, treated tastefully. It's what I have been finding lately. The Pros disappear in a day or two, sometimes after a few hours. The one's that can handle a conversation seem to be the one's worth the time and a little extra money.