I very rarely pay up front. I find that most real SP's don't really need that. I have seen one that wanted money upfront at a place where I have seen several, but I thought, okay, just for her piece of mind.
At my third visit, she still insisted and so I never saw her again.
The comfort level works both ways.
For me, if they need the money upfront, it feels like a transaction or the typical scammer depending upon who I am seeing (reputable or TOFFT).
It is everyone's choice, but I go by the adage of buyer beware.
It's not for everyone, but it has worked very well for me...ie. I NEVER get scammed.
And putting it in an envelope is just total bullshit! Where the F&^(^ did that ever come from? Oh, yes, the supposedly "reputable" SP's that need that in an envelope to keep it real! Too funny. How do they even know what's in there, and, if they need to check the contents, then what is the point of the envelope? Oh right, then they feel like they're not an SP but a ????