1)  Go the direct and honest route:  Tell the truth that you're having financial difficulty and can't afford her donation at the moment even though you really wanted wanted to see her. Tell her hopefully the next time she comes by you maybe in better financial shape.  

In this case there's an implied option for her. If she really needed the money and is willing to work with you (something is better than nothing) then she'd offer you a deal.

2)  Really save face: Tell her unfortunately you're being sent out of town by your company for training or going to visit your relative for a couple of weeks.

No option here cut and dry.

If it were me, I would respond with a polite email: "would love to see you, but cannot at this time due to special circumstances. Look forward to getting together on the next visit".

If she really wants to know why, she'll ask.  

By the way, not to burst your bubble, but you are probably not the only recipient of her email.  😏

.its a business transaction. Once you realize that your problem is solved.

Don't put too much information. Like someone said she is not the only recipient of the email (likely has an assistant or some such). Say you cant make it, cite 'special circumstances' or 'a lot going on in my life right now'.

You can say unfortunately you will not be able to see her on this visit you have some things you need to handle.But to let you know when she returns hopefully you can see her the next time.
I think you are overthinking this a bit.I am sure she will understand.

You don't want to seem like you're looking for a discount, but you don't want her to ignore you for future dates if you tell her you can't afford her this time. So don't explain. Just say you can't this time, but hope she will keep you in mind in the future. Good enough.

uhhh, tell her you can't afford to see her

you're under no obligation, then give her my contact info, I'm on a new quest

She is a professional sex worker---not your GF or wife. You are under absolutely no obligation to 'meet her expectations'.  

A simple and polite 'no thank you, maybe next time' is quite sufficient.  

If you would like to provide an explanation as to why you can't see her, that's entirely up to you. This would make some sense if this a provider with whom you have a lengthy history---or, perhaps, one you've  requested contact you when she was next in town.

But, even then, certainly not required or anything to have angst about.  

The truth....

Nothing wrong with just politely saying "current financial situation won't allow but would love to see you on next trip."

Who doesn't have from time to time financial woes. Tell her I'm sorry I can't see you due to financial issues. Hopefully we will see eachother soon. The End.

" save face for both of us "

Everyone has had cash flow issues in the past, well almost everyone anyway. She will understand.

And don't banter back and forth via email until you have the money and book a date. This is not said in any heart, but to tell you what will drive many ladies nuts.

I love chit chatting, but after a while - even if a guy is trying to get me to visit his city and would see me if I were there - over time, it takes a lot of extra time "pretending" to chit chat about it, and make imaginary plans. (Hopefully you haven't asked her to tour your area, and now she finally is and you're not available. This is why I don't book a tour around someone's request anymore. It never turns out when I'm there anyway.)

Just say "I'm sorry, I'm not available then." Maybe in the future when funds open up, you can do a fly me date. Then chit chat will be less tiresome for her.

Quite honestly, just watch for her ads. Book when you can. Until then, you really don't have to answer all the "why's" - even if the "why's" are demanded.

Tell her that you have been recruited by the CIA to go to Syria and find the head of ISIS and chop his head off, so it's a bad time for you, but feel free to contact you in the future.

 
What

She read your post.

If you tell her anything but the truth she will know you are a liar.

Also if she read your post she knows you are looking for suggested lies, and or BS stories.

What are the chances she will trust you in the future, that is if there is a future  
between the two of you.

 
Give the truth a shot .

 
Thank you  
50 = 5

The business savvy providers will continue to contact you even when you have said no more than once, as they know how to keep track of past clients. They know that there is a time when business may be sparse, so it will always be good to get the word out to past satisfied customers.  

I was contacted by one a third time, even after I gave her two previous declines and told her I didn’t have the funds. It didn’t stop her from getting her message out to me when she was in town. And, two years later, I did say yes.

So it happens, not so much that you’re important to her or not; it’s just that she is keen in getting business when she needs it and she will pull out all the stops to make sure she gets it.

I like the type of woman who knows how to work it without getting caught up with trying to second guess whether a client is sincere or not. They know how to go with the flow and will not rule out that present unavailability equates to future unavailability.

I get the impression that you really like her; but you can also consider taking a chance on trusting that she will come around again if this is how she continues to make her living. I wouldn’t over think it with worry if you tell her the truth

that way it does not seem that you are bargaining. Then be honest. Nothing wrong with it,  
And she knows you, so one can see who has a shady character and who is genuine.