Smoking hot SB, late 20's states that she likes my profile.  We exchange a few emails and she says all the right things.  We live in different cities.  Offers the following arrangement:  1) I fly her in once or twice a month; 2) pay her a per visit price; 3) if we connect, then convert her to a monthly allowance.

I'm not as negative as the previous responder, but really dude, why would you spend any money just to meet a girl just to find out if there's chemistry?  I've never done whqt you are contemplating, the math just doesn't work out.  The closest I ever came was a smokin hot girl who said she loves sex and loves pleasing her men.  OK so far.  She also said that if I would pay for her plane fare she would not expect me to give her any other financial support.  OK again.  But of course it was TGTBT and she ghosted before we got any farther.  I've had many SBs request money just for an initial coffee meeting.  I always decline by saying I've been scammed by women who promised me much, took my money and then vanished.  And also I think we should be equally interested in each other, at least equally willing to risk wasting an hour on meeting for coffee.  Flying this girl in without having met her first seems really risky.  I guess if she's hot enough I'd be tempted too, bot ONLY if she is willing to understand that the Sugar flows in her direction if and only if the intimacy has been shared. As for the amount, take your normal gift per visit amount, subtract her airfare and her hotel costs and offer her what's left, if anything. In my case that would be less than zero.

Thanks for the response.  When something seems TGTBT, it probably is.  I will continue to engage via email and phone.  If she demonstrates patience and doesn't ghost me, I will be surprised.

Unless you live in Pussy Siberia, I wouldn't even consider flying a POT SB in to meet me.

This applies to civvie dating as well. Back when I was dating online more than 20 years ago, I met a woman in Seattle on match.com. We exchange emails and chatted on the phone multiple times. We seemed to click and she asked me to visit her. Like a fool smitten in love, I bought a $400 ticket. The day before the visit, she turned radio silent of course. She wouldn't answer my phone calls or replied to my emails. I ended up eating the ticket. At least I didn't book a hotel room because she told me I could stay at her place. A few days later, she replied and told me she got cold feet. I flew off the handle and needless to say things ended badly.

The second you buy her a plane ticket it's belongs to her. She can change the destination to were ever she wants. Sure it will cost her a change fee, but she now owns the ticket not you, but she will have to give you her real name for that. I am guessing she will ask for you to send her the money so she can buy the ticket herself.

Yep, she reached out first.  And I don't live anywhere close to Pussy Siberia.  This is an obvious pass!

What you're willing to offer for the initial visit? Correct answer is zilch.
Looks like you live in a major metropolitan area and have seen more than a handful of pros. Here's my advice:

Great post and good advice.  I am relatively new to the SB game and would appreciate any and all guidance. What is the "correct" way to approach SB's?

Predictably, the smoking hot, out-of-town, SB declined my offer of getting to know each other via phone and skype over the next few months prior to me considering flying her out.  

describe it as being respectful, but demanding, and projecting an air of confidence without getting cocky. It also really helps to be relaxed and have a sense of humor. Especially for newer SB's who may be nervous about the process, they are really looking for you to lead the way and feel that you will take care of them. You need to make sure that they are clear about what you expect from them. You should always try to frame things in mutually beneficial terms. It's also hard to over-emphasize that there should never be any hint of desperation on your part. So, for example, the idea of flying some girl you've never met in when you live in a major metropolitan area would just set the whole arrangement off on the wrong foot. Any half-witted girl would think "what's wrong with this guy that he can't find a decent looking girl to get with in his city?"
It should never feel like you are over-reaching or overly eager when you approach these girls.
Some guys feel that it's a little like picking up a girl in a bar. In reality, it's a lot easier because, if you do it right, she's already told you what her price is and all you need to do is not come across as a creep/perv or weirdo in person to score. The whole thing will get a lot easier and feel a lot more natural after you've bagged your first few BCD's. I would say just get out there and practice. Before you know it, you'll have more SB's than you can handle.

I exchanged messages with one of my POT SB and she was willing to travel, 20s student, we did FaceTime a couple of times to see each other, she agreed for 1K on top of hotel and flight, her return ticket was $189 and I need a hotel even to see local SBs so the hotel expenses should not be considered but that was another $300 for two nights. We spent three days together so it was well worth it, six sessions will cost much more and good providers charge a lot for weekend trips.
So I suggest a 1K on top of hotel/travel should be enough for a 20 year old if there is a connection.