Well in light of this, I would say step away and keep away.
"Mary" is not coming across too well in this, in terms of her business acumen and her understanding of her actions. She really, really needs to understand her motivation for donating to the raffle, and she cannot for her own sanity project onto others that she gave a free cut and blow.
She didn't.
What she did was to donate to a local cause. Trouble is, she doesn't understand this, and she doesn't understand her "why" factor. There should be only one of three reasons (or indeed both) for a small business donating to a local raffle:
One, to support the cause.
Two, to win new business, and to up-sell her services while she was at it.
Three, to get rid of something they don't want.
We have no idea here about the first point, but on the second point it was clear that she succeeded, as you went to her salon for the first time, to claim the very prize that took you there, and you upgraded to a colour process too. This is exactly how it's meant to work, except that going forward you're supposed to be so delighted with your treatment that you'll tell everyone about it and hopefully will return for more.
Mary had all of this in buckets. The moment she realised that you were going to charge for the services she wanted you to provide, is the moment she should have absolutely stopped speaking and accepted that no matter what, she was going to have to pay or else not have those services. End. Of. Story.
But she didn't, at least based on what you've said. She went on to say how disappointed she is. At that point, you -as the golden customer who was thrilled with your Barnett Fair and all that she'd done to it & was going to tell everyone how much so- will have decided that none of this is worth the hassle. So Mary screwed herself over at that point...if she is so blind as not to see that she's not lost a "free" haircut but has in fact lost all the rewards she was liable to reap as a result of her initial investment, there's no hope for her.
And you - as a service provider- need to look out for people like this as they won't be easy to work for. FWIW, you've been lucky that Mary has shown you what she'll be like as client.